Yet another Brew Variables PR

[calculuschild]

Building on #3173, I think this is a pretty good syntax that does everything everyone wants.

Deployed to https://homebrewery-pr-3199.herokuapp.com/

Notes:

• Imperative definition works (i.e. variables can hold different values at different points in the document).
• Double interpolation is not possible (i.e., composing variable names out of other variables).
• Variable assignments inside of other variable assignments is not possible.
• Variables are hoisted if not yet defined when called. Uses the latest possible contents of that variable.

Three syntaxes:

syntax	description
[var]:content	Assigns a variable
[var](content)	Assigns a variable and outputs it
[var]	Outputs a variable

Examples:

syntax	output
[var]: Variable Contents	Assigns "Variable Contents" to var
[var]: Variable Contents on two or three or more lines	Assigns "Variable Contents\non two\nor three\nor more lines" to var
[var]: | h1 | h2 | |----|----| | c1 | c2 |	Assigns "| h1 | h2 |\n|----|----|\n| c1 | c2 | to var (and can later be rendered as a table)
$[var](Variable Contents)	Assigns "Variable Contents" to var and outputs that value
$[var](I love $[var2] and $[var3])	Assigns "I love var2 contents and var3 contents" to var and outputs that value
$[var]	Outputs var contents
[var]	outputs the variable contents as a link, if formatted as a valid link
![var]	outputs as an image, if formatted as a valid image
$[var]: Variable Contents or ![var]: Variable Contents	Identical to [var]: Variable Contents . Links, images, and variables all share the same global list. The ! or $ prefix only matters when the variable is being expressed
[var](Variable Contents) or 	Identical to assignment via $[var](Variable Contents), but outputs as a link or image if contents are a valid link format
$[num1 + num2 * (num3 - round(5.5))]	If +, -, *,/,^,(, or ) are found in the variable name, the whole variable is parsed mathematically with correct order of operations. Only parses if every variable is defined (hoisting works), and evaluate to a number, and the expression is valid. Supports round(x).

Math

Math currently supports the following function names: round(), floor(), ceil().
It also allows for () nesting operations.

So yes, you can do incrementing tables like this:

There are $[TableNum] tables in this document. // Final value of $[TableNum] gets hoisted up:
                                               //"There are 2 tables in this document."

$[TableNum]: 0 // Initialize to 0

$[TableNum]: $[TableNum + 1] // TableNum = 1

##### $[TableRefKnights](Table $[TableNum]: Horse Type and Quality)

...

$[TableNum]: $[TableNum + 1] // TableNum = 2

##### $[TableRefDragons](Table $[TableNum]: Dragons of the Realm)

[ericscheid]

How would one assign the string "https://example.com/" to a variable and then have it rendered as (literally) https://example.com/ ?

For an authoring system that produces print-destined output, being unable to print a url sounds like a problem.

I don't want printed documents that read as "For more details, visit our website at PublisherWebsite."

[ericscheid]

I'm a bit worried that double-interpolation might be setting us up for some recursion headaches.

[5e-Cleric]

How would one assign the string "https://example.com/" to a variable and then have it rendered as (literally) https://example.com/ ?

For an authoring system that produces print-destined output, being unable to print a url sounds like a problem.

I don't want printed documents that read as "For more details, visit our website at PublisherWebsite."

$[var]:https://example.com/ 
$[var]:(https://example.com/)

$[var]

first line is just assignment, second is assignment and output, third is just output
This worked just fine to output what you ask for in the deployment.

for clarification:

[var] will output equal to [var](https://example.com/)
$[var] will output equal to [https://example.com/](https://example.com/)

[calculuschild]

How would one assign the string "https://example.com/" to a variable and then have it rendered as (literally) https://example.com/ ?

Just use $[var]:(https://example.com/)

The $ indicates that it should be output as a string instead of a link.

[calculuschild]

I'm a bit worried that double-interpolation might be setting us up for some recursion headaches.

I'm not sure what you mean by double-interpolation.

Recursion would be handled by tracking a list of the variables you are currently inside and stop processing if we try to enter a nested variable already on that list.

[ericscheid]

I'm not sure what you mean by double-interpolation.

Interpolation is replacing variable references in a string with the value of those variables.

Double interpolation is replacing variable references in a string with the value of the variable named in those variables.

var foo = "some string"; // a string assigned to foo
var bar = `template with ${foo}`; // → "template with some string" (single interpolation)
var qaz = "foo"; // the string "foo" assigned to qaz
var qax = `template ${${qaz}}`; // the qaz variable is double interpolated, ultimately inserting the value of $foo

(I've also worked with systems which supported stuff like Set Field By Name[ variable_of_field_name, value_to_assign], but that's just more madness).

[calculuschild]

Double interpolation is replacing variable references in a string with the value of the variable named in those variables.

Ah ok. This PR isn't doing any double-interpolation by that definition so that shouldn't be a concern. I dont think it's even possible the way the code is set up.

Every example I listed above is "single interpolation".

[5e-Cleric]

Error list:

• When using parentheses, no value is not expected, breaks the whole tool
• String variables get lowercase'd
• Image syntax completely broken
• Variables not working inside other syntaxes, such as links (I don't know what i meant by that, so don't know if its fixed :))))) )

[5e-Cleric]

$[var]:() will still break the brew completely.

[calculuschild]

$[var]:() will still break the brew completely.

Should be fixed. Now has same behavior as $[var]: where it just isn't parsed as a variable until it has some content, so empty () is not recognized.