Parameterized goals

The idea for this is inspired by #112. This should be much better and more generic alternative to #96.

This should allow such rewrite.

Related to this. Obviously this is being revised.

@goal files_created @params A B
@depends_on file_created @args A
@depends_on file_created @args B
@depends_on file_created @args '/tmp/file'
@depends_on goal_3_args @args A '/tmp/file' B

@goal file_created @params F
@reached_if [[ -f "$F" ]]
  echo hello > "$F"

Q. Default values.

No

Q. Optional values.

No

Q. How to pass var argument?

• @VAR
  • Cons: non-uniform syntax
  • Using this form can help getting rid of @args and allow mixing dependencies
  • But this needs to disambiguate the case when goal is named @name
• But not that simple… what about literal values?
• "${VAR}" but only this form, not "aaa${VAR} bbb"
• VAR, literal values must be quoted (with single quotes or dollar-single quotes to disallow substitutions)

Q. Do we even need keyword @args?

Looks like we don’t need it to disambiguate. BUT this complicates resolution.

Q. Do we need keyword @params?

Looks like yes

• for consistency
• for ease of parsing

Q. Do we allow to include parameterized goal in @depends_on together with other goals? Or only single?

No. @args will be only allowed in pos=3. All items afterwards are considered args.

Q. Shall we restrict the param name to Name123? [A-Z][A-Za-z0-9_]*

Yes, this is a good idea / convention.

Q. Can we make parameterized goals resolution during parsing? We might need to know the number of params for a goal which is not available yet, since goal may come later.

Looks like this is only possible if we restrict the syntax to

@depends_on param_goal @args 'hello'

I.e. when @args is at pos=3

@depends_on param_goal ( 'hello' A 'world' ) # needs more parsing

Q. Allow calling parameterized goal from CLI?

No

Q. Allow listing PG?

No. But we list “instantiated” goals instead.

Q. Loops detection.

Based on goal name only. I.e. disallow depending PG on itself in any way.

Q. What can be @args VAR?

Only:

• what’s in @define (not now, maybe in future)
• any VAR in @params of this goal
• All other cases must cause error.

Q. Mechanism for "instantiation"

Also here. Need to adjust -d option. Should list instantiated goals in form

• pg1@hello
• $'pg2@hello@with \''
• nonpg

1. Build tree no-params : detect loops
2. Build tree non-instantiated
3. Instantiate. How?
   • On encounter @depends_on generate instantiated. This needs to go in-depth.

Parameterized goals vs existing features

PG + @glob

Disallow

PG + @private

Instantiated goals will be private

PG + @lib

Should work as expected. PG vars should be accessible in lib code.

PG + @reached_if

Should work as expected. PG vars should be accessible in @reached_if code.

PG + @doc

Should work as expected. @doc should just copy to instantiated goals.