LUA ComonPitfalls - Revision history

Flozi: Category:Lua despite its problems

2013-03-09T21:27:50Z

Category:Lua despite its problems

← Older revision		Revision as of 22:27, 9 March 2013
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	And thats a hardone to find. Because if you read it up again, you will switch languages in your head.. its one of those things you do without thinking. Same stuff can happen if you are fluent with several languages, and translate your variables, because you are distracted for a moment.		And thats a hardone to find. Because if you read it up again, you will switch languages in your head.. its one of those things you do without thinking. Same stuff can happen if you are fluent with several languages, and translate your variables, because you are distracted for a moment.

	~~<br/>~~		[[Category:Lua]]

Gajop: removed useless/wrong information and cleaned up some typos

2012-12-26T15:28:06Z

removed useless/wrong information and cleaned up some typos

Show changes

Picassoct at 11:04, 24 March 2012

2012-03-24T11:04:59Z

← Older revision		Revision as of 12:04, 24 March 2012
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	<span style="color:#00ff00"> while(true) do		<span style="color:#00ff00"> while(true) do
	info=Spring.GetMyInfo(unitID)		info=Spring.GetMyInfo(unitID)
	if info == true then		if info == true then
	--do this		--do this
	else		else
	--do that		--do that
	end		end
	Sleep(150)		Sleep(150)
	end		end
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	Now that sounds like something made up to impress. But well, this occurs mainly if you do complicated math or call external functions. You write something down, which is in the language you are currenty thinking in quite accurate. But meanwhile you have forgotte all about the LUA-Syntax. Example?		Now that sounds like something made up to impress. But well, this occurs mainly if you do complicated math or call external functions. You write something down, which is in the language you are currenty thinking in quite accurate. But meanwhile you have forgotte all about the LUA-Syntax. Example?

	<span style="color:#00ff00">x=32+ math.sin(phi) * x~~<br/>~~</span>		<span style="color:#00ff00">x=32+ math.sin(phi) * x</span>

	<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^x</span>		<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^x</span>

	If you write this.. its pure truth. Written down on paper its pure truth. If you calc it back, its still pure truth. Executed in Lua it will do strange things, you wont find easily without debugger. Thats because the x is allready changed when it goes into the second line. So a accurate Version of this would look like:		If you write this.. its pure truth. Written down on paper its pure truth. If you calc it back, its still pure truth. Executed in Lua it will do strange things, you wont find easily without debugger. Thats because the x is allready changed when it goes into the second line. So a accurate Version of this would look like:

	<span style="color:#00ff00">tempXofOld=x x=32+ math.sin(phi) * x ~~<br/>~~</span>		<span style="color:#00ff00">tempXofOld=x</span>

			<span style="color: rgb(0, 255, 0)">x=32+ math.sin(phi) * x</span>

	<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^tempXofOld</span>		<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^tempXofOld</span>

Picassoct at 11:04, 24 March 2012

2012-03-24T11:04:00Z

← Older revision		Revision as of 12:04, 24 March 2012
Line 125:		Line 125:

	<span style="color:#00ff00"> while(true) do		<span style="color:#00ff00"> while(true) do
	info=Spring.GetMyInfo(unitID)		info=Spring.GetMyInfo(unitID)
	if info == true then		if info == true then
	--do this		--do this
	else		else
	--do that		--do that
	end		end
	Sleep(150)		Sleep(150)
	end		end
	</span>		</span>

Line 148:		Line 148:
	'''SIG_ANYTHING=4'''		'''SIG_ANYTHING=4'''

	Threads are Started and if you use SetSignalMask(SIG_SOMETHING) you assing them a unique Number, that must be the power of two(1,2,4,8,16,32...). To understand SignalMasks you need to understand the binary representation of this numbers.		Threads are Started and if you use SetSignalMask(SIG_SOMETHING) you assing them a unique Number, that must be the power of two(1,2,4,8,16,32...). To understand SignalMasks you need to understand the <u>'''binary'''</u>representation of this numbers.

	SIG_ONE = 1            SIG_SOMETHING= 10            SIG_ANYTHING= 100		SIG_ONE = 1            SIG_SOMETHING= 10            SIG_ANYTHING= 100
Line 154:		Line 154:
	Notice the difference? Every one of this 1s represent a Switch, that can be either on, or off. If you Send a Signal Signal(SIG_ONE) this will find the thread (and its decendants) and pull the plug.  What happens if we would use a uneven number? Signal(3) for example?  It would result into Signal(11) (3 beeing 11 in binary) and pull the plugs of all threads marked by the SignalMasks 2 and 1. Now if you assign a threads decendant thread another number, it becomes independent from the father Thread. Handle with care.		Notice the difference? Every one of this 1s represent a Switch, that can be either on, or off. If you Send a Signal Signal(SIG_ONE) this will find the thread (and its decendants) and pull the plug.  What happens if we would use a uneven number? Signal(3) for example?  It would result into Signal(11) (3 beeing 11 in binary) and pull the plugs of all threads marked by the SignalMasks 2 and 1. Now if you assign a threads decendant thread another number, it becomes independent from the father Thread. Handle with care.

	19. Internal Language Changes:		'''19. Internal Language Changes:'''

	Now that sounds like something made up to impress. But well, this occurs mainly if you do complicated math or call external functions. You write something down, which is in the language you are currenty thinking in quite accurate. But meanwhile you have forgotte all about the LUA-Syntax. Example?		Now that sounds like something made up to impress. But well, this occurs mainly if you do complicated math or call external functions. You write something down, which is in the language you are currenty thinking in quite accurate. But meanwhile you have forgotte all about the LUA-Syntax. Example?
	~~x=32+ math.sin(phi) * x~~
	~~y=64 + 12 *math.cos(phi)^x~~

	If you write this.. its pure truth. Written down on paper its pure truth. If you calc it back, its still pure truth. Executed in Lua it will do strange things, you wont find easily without debugger. Thats because the x is allready changed when it goes into the second line. So a accurate Version of this would look like:		<span style="color:#00ff00">x=32+ math.sin(phi) * x<br/></span>
	tempXofOld=x
	x=32+ math.sin(phi) * x		<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^x</span>
	y=64 + 12 *math.cos(phi)^tempXofOld
			If you write this.. its pure truth. Written down on paper its pure truth. If you calc it back, its still pure truth. Executed in Lua it will do strange things, you wont find easily without debugger. Thats because the x is allready changed when it goes into the second line. So a accurate Version of this would look like:

			<span style="color:#00ff00">tempXofOld=x x=32+ math.sin(phi) * x <br/></span>

			<span style="color:#00ff00">y=64 + 12 *math.cos(phi)^tempXofOld</span>

	And thats a hardone to find. Because if you read it up again, you will switch languages in your head.. its one of those things you do without thinking. Same stuff can happen if you are fluent with several languages, and translate your variables, because you are distracted for a moment.		And thats a hardone to find. Because if you read it up again, you will switch languages in your head.. its one of those things you do without thinking. Same stuff can happen if you are fluent with several languages, and translate your variables, because you are distracted for a moment.

			<br/>'''20. A visit to the zoo:'''

	~~20. A visit to the zoo:~~
	Lets visit the Zoo of lua-errors, and lets see what the erorr messages (if you get any actual mean).		Lets visit the Zoo of lua-errors, and lets see what the erorr messages (if you get any actual mean).

Picassoct at 11:01, 24 March 2012

2012-03-24T11:01:58Z

← Older revision		Revision as of 12:01, 24 March 2012
Line 154:		Line 154:
	Notice the difference? Every one of this 1s represent a Switch, that can be either on, or off. If you Send a Signal Signal(SIG_ONE) this will find the thread (and its decendants) and pull the plug.  What happens if we would use a uneven number? Signal(3) for example?  It would result into Signal(11) (3 beeing 11 in binary) and pull the plugs of all threads marked by the SignalMasks 2 and 1. Now if you assign a threads decendant thread another number, it becomes independent from the father Thread. Handle with care.		Notice the difference? Every one of this 1s represent a Switch, that can be either on, or off. If you Send a Signal Signal(SIG_ONE) this will find the thread (and its decendants) and pull the plug.  What happens if we would use a uneven number? Signal(3) for example?  It would result into Signal(11) (3 beeing 11 in binary) and pull the plugs of all threads marked by the SignalMasks 2 and 1. Now if you assign a threads decendant thread another number, it becomes independent from the father Thread. Handle with care.

			19. Internal Language Changes:

			Now that sounds like something made up to impress. But well, this occurs mainly if you do complicated math or call external functions. You write something down, which is in the language you are currenty thinking in quite accurate. But meanwhile you have forgotte all about the LUA-Syntax. Example?
			x=32+ math.sin(phi) * x
			y=64 + 12 *math.cos(phi)^x

	19. A visit to the zoo:		If you write this.. its pure truth. Written down on paper its pure truth. If you calc it back, its still pure truth. Executed in Lua it will do strange things, you wont find easily without debugger. Thats because the x is allready changed when it goes into the second line. So a accurate Version of this would look like:
			tempXofOld=x
			x=32+ math.sin(phi) * x
			y=64 + 12 *math.cos(phi)^tempXofOld

			And thats a hardone to find. Because if you read it up again, you will switch languages in your head.. its one of those things you do without thinking. Same stuff can happen if you are fluent with several languages, and translate your variables, because you are distracted for a moment.


			20. A visit to the zoo:
	Lets visit the Zoo of lua-errors, and lets see what the erorr messages (if you get any actual mean).		Lets visit the Zoo of lua-errors, and lets see what the erorr messages (if you get any actual mean).

Picassoct at 10:47, 24 March 2012

2012-03-24T10:47:46Z

← Older revision		Revision as of 11:47, 24 March 2012
Line 156:		Line 156:


	19.		19. A visit to the zoo:
			Lets visit the Zoo of lua-errors, and lets see what the erorr messages (if you get any actual mean).

Picassoct at 19:02, 18 March 2012

2012-03-18T19:02:37Z

← Older revision		Revision as of 20:02, 18 March 2012
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	<span style="color:#ff0000">''if (boolOne == true and x > 3.14) or (foo==bar) then''</span><span style="color:#f0ffff">''can be converted into''</span>		<span style="color:#ff0000">''if (boolOne == true and x > 3.14) or (foo==bar) then''</span><span style="color:#f0ffff">''can be converted into''</span>

	<span style="color:#00ff00">''function checkThem(boolOne,x,foo,bar) if (boolOne == true and x > 3.14) or (foo==bar) then''~~<br/>~~</span>		<span style="color:#00ff00">''function checkThem(boolOne,x,foo,bar) if (boolOne == true and x > 3.14) or (foo==bar) then''</span>

	<span style="color:#00ff00">''return true''</span>		<span style="color:#00ff00">''return true''</span>
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	<span style="color:#00ff00">''else''</span>		<span style="color:#00ff00">''else''</span>

	<span style="color:#00ff00">''return false''~~<br/>~~</span>		<span style="color:#00ff00">''return false''</span>

	<span style="color:#00ff00">''end''</span>		<span style="color:#00ff00">''end''</span>
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	is slow. Everytime the first table is called the value is taken, then the second big value is called, rising the chance to push the first table out of memory. Thus a constant loading and writting occurs in the background.		is slow. Everytime the first table is called the value is taken, then the second big value is called, rising the chance to push the first table out of memory. Thus a constant loading and writting occurs in the background.

	<span style="color:#00ff00">ArmedUnits -- a table that contains the unit and the weapon bundled together~~<br/>~~</span>		<span style="color:#00ff00">ArmedUnits -- a table that contains the unit and the weapon bundled together</span>

	<span style="color:#00ff00">for i=1, 9000,1 do</span>		<span style="color:#00ff00">for i=1, 9000,1 do</span>

	<span style="color:#00ff00"~~><br/~~>ArmedUnits[i].unit</span>		<br/><span style="color:#00ff00">ArmedUnits[i].unit</span>

	<span style="color:#00ff00">weapon=ArmedUnits[i].weapon</span>		<span style="color:#00ff00">weapon=ArmedUnits[i].weapon</span>
Line 105:		Line 105:
	'''15. Syntactical Insecuritys?'''		'''15. Syntactical Insecuritys?'''

	Spring over tthe time has incoporated scripts from diffrent languages (cob/bos/lua) scripts and some of those calls are rather vague described in the wiki. So how does this COB Get/Set work? Best sollution, google it. Really. Somewhere someone allready has used it, and you can see it, working.		Spring over tthe time has incoporated scripts from diffrent languages (cob/bos/lua) scripts and some of those calls are rather vague described in the wiki. So how does this COB Get/Set work? Best sollution, google it. Really. Somewhere someone allready has used it, and you can see it, working.

	'''14.Forgotten Globals'''		'''14.Forgotten Globals'''
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	Nil is Nihilistic. It takes functions with it it, everything that touches it becomes unstable, antimatter. A Variable initialised with nil will resolve in a 0 no matter what you put in through other functions. You know the checks. Use them.		Nil is Nihilistic. It takes functions with it it, everything that touches it becomes unstable, antimatter. A Variable initialised with nil will resolve in a 0 no matter what you put in through other functions. You know the checks. Use them.

	~~More to come.. thats for certain.~~		<br/>'''16. BackUP'''
	'''16. BackUP'''

	Not against data loss through hardware failure or viruses, but to have a safecopy should you screw up. There is stuff that will crawl into a overworked tired mind at 4 in the morning that you will find brilliant. And the next moment, you want to go back, all you find is a NeedMoreSleep() function with a lame pun in it.		Not against data loss through hardware failure or viruses, but to have a safecopy should you screw up. There is stuff that will crawl into a overworked tired mind at 4 in the morning that you will find brilliant. And the next moment, you want to go back, all you find is a NeedMoreSleep() function with a lame pun in it. Use a Subversion controll system, use a simple on for the start (like Mecurial). Advanced people will recommend you advanced tools. There is no shame in using the easier option if that one allows you to archieve your goals.
	Use a Subversion controll system, use a simple on for the start (like Mecurial). Advanced people will recommend you advanced tools. There is no shame in using the easier option if that one allows you to archieve your goals.
			'''17. Dont Poison the Well''' Sometimes you need Information for a Unit, and you create a Sensor-Thread such as this.

			<span style="color:#00ff00">local function senSoricLoop()
			</span>

			<span style="color:#00ff00"> while(true) do
			info=Spring.GetMyInfo(unitID)
			if info == true then
			--do this
			else
			--do that
			end
			Sleep(150)
			end
			</span>

			<span style="color:#00ff00">end
			</span>

			Poisoning the well means, instead of writting a second while loop to give in to the temptation to just falsify the sensoric data. In this case making the info global, and setting it to false every Sleep(20). This thing is nasty, it will result in unpredictable behaviour, a unit that seemingly at random sometimes spasms. Avoid at all cost.

			<br/>'''18. SignalMasks for Threads (Thx to Tobi for this one)'''

			'''SIG_ONE=1'''

			'''SIG_SOMETHING=2'''

			'''SIG_ANYTHING=4'''

			Threads are Started and if you use SetSignalMask(SIG_SOMETHING) you assing them a unique Number, that must be the power of two(1,2,4,8,16,32...). To understand SignalMasks you need to understand the binary representation of this numbers.

			SIG_ONE = 1            SIG_SOMETHING= 10            SIG_ANYTHING= 100

			Notice the difference? Every one of this 1s represent a Switch, that can be either on, or off. If you Send a Signal Signal(SIG_ONE) this will find the thread (and its decendants) and pull the plug.  What happens if we would use a uneven number? Signal(3) for example?  It would result into Signal(11) (3 beeing 11 in binary) and pull the plugs of all threads marked by the SignalMasks 2 and 1. Now if you assign a threads decendant thread another number, it becomes independent from the father Thread. Handle with care.



			19.

Picassoct at 19:38, 14 March 2012

2012-03-14T19:38:47Z

← Older revision		Revision as of 20:38, 14 March 2012
Line 116:		Line 116:

	More to come.. thats for certain.		More to come.. thats for certain.
			'''16. BackUP'''

			Not against data loss through hardware failure or viruses, but to have a safecopy should you screw up. There is stuff that will crawl into a overworked tired mind at 4 in the morning that you will find brilliant. And the next moment, you want to go back, all you find is a NeedMoreSleep() function with a lame pun in it.
			Use a Subversion controll system, use a simple on for the start (like Mecurial). Advanced people will recommend you advanced tools. There is no shame in using the easier option if that one allows you to archieve your goals.

Picassoct at 19:29, 14 March 2012

2012-03-14T19:29:53Z

← Older revision		Revision as of 20:29, 14 March 2012
Line 103:		Line 103:
	Do not leave this useless compares in the code. Instead use the Spring.Echo alone.  Then if the release is closing in use Text Replacement to Replace Spring.Echo with --Spring.Echo.		Do not leave this useless compares in the code. Instead use the Spring.Echo alone.  Then if the release is closing in use Text Replacement to Replace Spring.Echo with --Spring.Echo.

	15. Syntactical Insecuritys?		'''15. Syntactical Insecuritys?'''

	Spring over tthe time has incoporated scripts from diffrent languages (cob/bos/lua) scripts and some of those calls are rather vague described in the wiki. So how does this COB Get/Set work? Best sollution, google it. Really. Somewhere someone allready has used it, and you can see it, working.		Spring over tthe time has incoporated scripts from diffrent languages (cob/bos/lua) scripts and some of those calls are rather vague described in the wiki. So how does this COB Get/Set work? Best sollution, google it. Really. Somewhere someone allready has used it, and you can see it, working.

	'''14.Forgotten Globals'''		'''14.Forgotten Globals'''

	Declared aeons ago, forgotten by you and used in the assumption they never existed. And now you fill them with diffent values in a function, wondering at the strange sideeffects.		Declared aeons ago, forgotten by you and used in the assumption they never existed. And now you fill them with diffent values in a function, wondering at the strange sideeffects.

	'''15. Nil'''		'''15. Nil'''

	Nil is Nihilistic. It takes functions with it it, everything that touches it becomes unstable, antimatter. A Variable initialised with nil will resolve in a 0 no matter what you put in through other functions. You know the checks. Use them.		Nil is Nihilistic. It takes functions with it it, everything that touches it becomes unstable, antimatter. A Variable initialised with nil will resolve in a 0 no matter what you put in through other functions. You know the checks. Use them.

	More to come.. thats for certain.		More to come.. thats for certain.

Picassoct at 19:29, 14 March 2012

2012-03-14T19:29:20Z

← Older revision		Revision as of 20:29, 14 March 2012
Line 103:		Line 103:
	Do not leave this useless compares in the code. Instead use the Spring.Echo alone.  Then if the release is closing in use Text Replacement to Replace Spring.Echo with --Spring.Echo.		Do not leave this useless compares in the code. Instead use the Spring.Echo alone.  Then if the release is closing in use Text Replacement to Replace Spring.Echo with --Spring.Echo.

	~~<br~~/~~>'''13~~.~~Tail Calls:'''~~		15. Syntactical Insecuritys?
			Spring over tthe time has incoporated scripts from diffrent languages (cob/bos/lua) scripts and some of those calls are rather vague described in the wiki. So how does this COB Get/Set work? Best sollution, google it. Really. Somewhere someone allready has used it, and you can see it, working.

			'''14.Forgotten Globals'''
			Declared aeons ago, forgotten by you and used in the assumption they never existed. And now you fill them with diffent values in a function, wondering at the strange sideeffects.

			'''15. Nil'''
			Nil is Nihilistic. It takes functions with it it, everything that touches it becomes unstable, antimatter. A Variable initialised with nil will resolve in a 0 no matter what you put in through other functions. You know the checks. Use them.

	~~<br/>~~More to come.. thats for certain.~~</nowiki>~~		More to come.. thats for certain.