The Webel ‘$’ prefix convention for Strings and "String similar" Wolfram Language code

EXAMPLE: The '$' prefix convention is used for diagnostic functions of the Webel Devel` package that can accept a String or StringForm as the diagnostic '$msg' message argument to echo (typically styled) to the console.

EXAMPLE: The '$' prefix convention is used for the '$client' argument of a function that acts on behalf of (as a delegate of) another function, where the '$client' may be a Symbol (preferred) OR a String or StringForm if more detailed tracking is required (such as during debugging).

NB: where an argument may only accept a Symbol a '$' prefix is NOT used.

The '$' prefix indicates that the variable or argument must either by a String strictly (so $var_String) OR expects something "String-like" or something that will be used like text and could accept a String (but might still work with a StringForm or a Symbol).

There are other Webel conventions (such as the '$opt$', '$arg$' and '$k$' conventions we'll explore in the next slides) that strictly only use String.

For reference, some related Webel convention policy notes (explored in more detail also in later slides). For now it's recommended that you don't visit these links yet but instead just view the next slide:

Webel: Mathematica: CONVENTION: Where keys of Associations are Strings they are encapsulated as variables prefixed with '$k$' (promotes DRY and has many advantages, such as IDE prompting). Direct use of "Strings" as keys is WET and strongly discouraged!

Webel: Mathematica: CONVENTION: Option help holders use a String variable with the prefix '$opt$', a related '$info$opt$' String, a 'def$opt$' default value expression, and optional '$warn$opt$', '$tip$opt$', '$lab$opt$', and 'type$opt$' indicator ...

Webel: Mathematica: CONVENTION: Argument help holders use a String variable with the prefix '$arg$', a related '$info$arg$' String, a 'def$arg$' default value expression and/or 'req$arg$', and optional '$warn$arg$', '$tip$arg$, '$lab$arg$', 'type$arg$'..

Webel: Mathematica: CONVENTION: "pattern helpers" (which are not themselves Patterns) use the prefix '$pat$. Encapsulated Patterns use a 'pat$' prefix, and may use a '$pat$' pattern helper (such as an Alternatives).

Up next

The Webel $k$ prefix convention for Association String keys

Notes

[NAMING, PATTERN, POLICY]{STRICT} Webel: Mathematica: CONVENTION: Option help holders use a String variable with the prefix '$opt$', a related '$info$opt$' String, a 'def$opt$' default value expression, and optional '$warn$opt$', '$tip$opt$', '$lab$opt$', and 'type$opt$' indicator ...

[NAMING, PATTERN, POLICY]{STRICT} Webel: Mathematica: CONVENTION: Argument help holders use a String variable with the prefix '$arg$', a related '$info$arg$' String, a 'def$arg$' default value expression and/or 'req$arg$', and optional '$warn$arg$', '$tip$arg$, '$lab$arg$', 'type$arg$'..

[CONVENTION, NAMING, PATTERN, POLICY]{STRICT} Webel: Mathematica: CONVENTION: "pattern helpers" (which are not themselves Patterns) use the prefix '$pat$. Encapsulated Patterns use a 'pat$' prefix, and may use a '$pat$' pattern helper (such as an Alternatives).

[CONVENTION, NAMING, PATTERN, POLICY]{STRICT} Webel: Mathematica: CONVENTION: Where keys of Associations are Strings they are encapsulated as variables prefixed with '$k$' (promotes DRY and has many advantages, such as IDE prompting). Direct use of "Strings" as keys is WET and strongly discouraged!

[NAMING, OPTION, PATTERN, TIP]{OPTION} Mathematica: Webel: You CAN/MAY use $ in variable names and function names - just not as the first character before a Capital - and it's extremely useful. You won't get sent to Azkaban prison if do you use a $ character!