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BSL:Manual: Difference between revisions
explaining declaration and type spec; mentions of other sections are now links to them
(→Flow interrupt: moving "insider" statement to Introduction) |
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dmsg("Statement 2") | dmsg("Statement 2") | ||
The third example is in old-style syntax, which is discussed under | The third example is in old-style syntax, which is discussed under [[#Old vs. new syntax|Old vs. new syntax]]. | ||
===Compound statements=== | ===Compound statements=== | ||
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{dmsg("Statement 1"); dmsg("Statement 2"); dmsg("Statement 3");} | {dmsg("Statement 1"); dmsg("Statement 2"); dmsg("Statement 3");} | ||
The purpose of doing this is to group some statements under a header, which can be either a function declaration (see | The purpose of doing this is to group some statements under a header, which can be either a function declaration (see [[#Declaration|Declaration) or an "if" statement (see [[#Conditional|Conditional]]). | ||
===Comments=== | ===Comments=== | ||
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if [block of code begins here] | if [block of code begins here] | ||
Do not using trailing comments when not ending statements with semicolons (see | Do not using trailing comments when not ending statements with semicolons (see [[#Old vs. new syntax|Old vs. new syntax]] for explanation). | ||
In documentation outside of source code or script files, such as this page, comments are sometimes used to tell the reader something in a way that doesn't break the actual code, if the user should type it in exactly as it appears, comments and all. | In documentation outside of source code or script files, such as this page, comments are sometimes used to tell the reader something in a way that doesn't break the actual code, if the user should type it in exactly as it appears, comments and all. | ||
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===Declaration=== | ===Declaration=== | ||
Before using a function or a variable for the first time, you need to give some information on it. | |||
====var==== | ====var==== | ||
See | See [[#Variables/Variables]] for details on using variables. | ||
====func==== | ====func==== | ||
See | See [[#Functions|Functions]] for details on using functions. | ||
===Type specification=== | ===Type specification=== | ||
When declaring a variable or defining a function, you need to state what type of data is contained in that variable or what kind the function works with. | |||
Besides "void" | ====void, bool, int, float, string==== | ||
Besides "void" (used in function definitions to indicate "no type"), these are the types of data that can be assigned to variables, passed to functions, and returned by functions. See [[#Data types|Data types]]. | |||
===Conditional=== | ===Conditional=== | ||
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} | } | ||
The condition in the parentheses needs to evaluate to "true" or "false". For examples of operators, see | The condition in the parentheses needs to evaluate to "true" or "false". For examples of operators, see [[#Operators|Operators]]. | ||
The condition can technically also evaluate to an int value, which then is converted to true/false: | The condition can technically also evaluate to an int value, which then is converted to true/false: | ||
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if (7 - 8) # evaluates to true because it is non-zero | if (7 - 8) # evaluates to true because it is non-zero | ||
Be aware that BSL does not properly respect scope for blocks of code under "if" statements, so some actions like setting variables and using "return" will occur even if the surrounding "if" condition is false (see | Be aware that BSL does not properly respect scope for blocks of code under "if" statements, so some actions like setting variables and using "return" will occur even if the surrounding "if" condition is false (see [[#Flow interrupt|Flow interrupt]] for an example). A workaround for setting variables conditionally is to make the variable global, and under the "if" statement call a function that modifies that variable; the function call will not fire unless the "if" condition is true. | ||
The logical operators "and" and "or" can be used to string together multiple conditions: | The logical operators "and" and "or" can be used to string together multiple conditions: | ||
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The statements under "else" will never run. The "return" will actually kick in and the function will exit, even though the surrounding control statement did not evaluate to true. | The statements under "else" will never run. The "return" will actually kick in and the function will exit, even though the surrounding control statement did not evaluate to true. | ||
However, "return" is still useful for returning data to a calling function; see | However, "return" is still useful for returning data to a calling function; see [[#Functions|Functions]]. | ||
====sleep==== | ====sleep==== | ||
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===Loop=== | ===Loop=== | ||
BSL has no "for" or "while" statement, but "schedule-repeat-every" (see | BSL has no "for" or "while" statement, but "schedule-repeat-every" (see [[#Concurrency|Concurrency]]) can be used as a poor-man's loop (as long as you realize that there's no way to exit early). | ||
===Multi-threading=== | ===Multi-threading=== | ||
====fork, schedule-at, schedule-repeat-every==== | ====fork, schedule-at, schedule-repeat-every==== | ||
See | See [[#Concurrency|Concurrency]] for the use of these keywords. | ||
===Obsolete=== | ===Obsolete=== | ||
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You'll note that there is no multiplication or division. Bungie West was only concerned with creating enough scripting power to drive Oni, and they did not need "higher math" for this. | You'll note that there is no multiplication or division. Bungie West was only concerned with creating enough scripting power to drive Oni, and they did not need "higher math" for this. | ||
See | See [[#Data types|Data types]] to learn the details of how operators work between different data types. | ||
===Relational=== | ===Relational=== | ||
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==Data types== | ==Data types== | ||
When declaring a variable or a function (more on this under the | When declaring a variable or a function (more on this under the [[#Functions|Functions]] and [[#Variables|Variables]] sections), you must specify the type of data it contains, accepts, or returns: | ||
var int x; | var int x; | ||
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===void=== | ===void=== | ||
See | See [[#Functions|Functions]]. Variables cannot be type "void". | ||
===bool=== | ===bool=== | ||
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===Returning=== | ===Returning=== | ||
As mentioned under | As mentioned under [[#Flow interrupt|Flow interrupt]], "return" exits the function at that point. Because of the bug documented in that section, you cannot exit early from a function under some condition. Since "return" can thus only be placed at the end of a function, there is no point in using it at all unless you are going to pass back a value by placing a variable name after "return": | ||
func int add_ten(int input) | func int add_ten(int input) | ||