YENGconstant

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constant allows to define a constant value that is evaluated and all its occurrences in code are replaced by that value at compile time.<br>
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constant allows to define a constant value that is evaluated and all its occurrences in code are replaced by that value at compile time.
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its type is by the types are right side expression, and very confusing
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  constant endlimit = 0.1 // will be a float
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  Make sure to include yoptions; on second line of script.
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constant start = 1 // will be a integer
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constant idea = 2 + 3 // will be integer 5
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constant idea = 2 + 3.0 // will be string 5.0 since it is at compile time will mean integer 5
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constant badidea = "2" + 3 // will be string "23"
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This last example illustrates that mixed types, specially when one is a string, can be confusing, and should be avoid<br>
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Its type will be guessed from the types at right side expression, and can be confusing
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since will make harder to understand a script, the opposite of its purpose.
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other operations supported
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constant endlimit = 0.1 // will be a like float 0.1
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constant start = 1 // will be a like integer 1
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constant idea = 2 + 3 // will be like integer 5
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constant betteridea = idea + 3 // will be like integer 8
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constant otheridea = 2 + 3.0 // will be like float 5.0
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constant badidea = "2" + 3 // will be like string "23"
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Other operations supported
 
  & | ^ ~ for integer types
 
  & | ^ ~ for integer types
 
  - * / % for integer or float types
 
  - * / % for integer or float types
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note that evaluation order is not the best, the use of () is a must
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On expressions better use () to force and make clear the desired evaluation order
 
  constant ar = 2 + (2 & 1); //will be 2
 
  constant ar = 2 + (2 & 1); //will be 2
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  constant ar = 2 + 2 & 1; //will be 0, ie code did (2 + 2) & 1
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  constant ar = 2 + 2 & 1; //will be 0, ie will do (2 + 2) & 1 since + and & have same evaluation priority.
  
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possible the use of any operation should just be avoid.<br>
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Simple normal use will be to define a simple constant at top of program, easy to change later.
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better to only use to define a simple constant at top of program, easy to change later.
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  constant textureID = "0d3b69fe-1b6e-40f3-8e5f-933814df3b7b";
 
  constant textureID = "0d3b69fe-1b6e-40f3-8e5f-933814df3b7b";
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Saving the memory of a global variable.
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[[Category:Scripts]]

Revision as of 15:36, 20 November 2020

constant allows to define a constant value that is evaluated and all its occurrences in code are replaced by that value at compile time. 

Make sure to include yoptions; on second line of script.

Its type will be guessed from the types at right side expression, and can be confusing 

constant endlimit = 0.1 // will be a like float 0.1
constant start = 1 // will be a like integer 1
constant idea = 2 + 3 // will be like integer 5
constant betteridea = idea + 3 // will be like integer 8
constant otheridea = 2 + 3.0 // will be like float 5.0
constant badidea = "2" + 3 // will be like string "23"

Other operations supported 

& | ^ ~ for integer types
- * / % for integer or float types

On expressions better use () to force and make clear the desired evaluation order 

constant ar = 2 + (2 & 1); //will be 2
constant ar = 2 + 2 & 1; //will be 0, ie will do (2 + 2) & 1 since + and & have same evaluation priority.

Simple normal use will be to define a simple constant at top of program, easy to change later. 

constant textureID = "0d3b69fe-1b6e-40f3-8e5f-933814df3b7b";

Saving the memory of a global variable.

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