Question: Is it possible to use recipe parameters as part of a new parameter before it is passed to the dependencies?

[antis81]

This issue is a bit related to the questions #1988 and #2341. Instead of just forwarding the recipe parameters I would like to create a new (not necessarily variadic) parameter which in turn is forwarded to the recipe.

For a simple example assume a game engine for board/card games and we like to select the game and provide additional parameters from commandline (number of players, size, colors, etc.):

just play-multiplayer "ludo" 6
just play-singleplayer "solitaire"

I am looking for a more flexible way to inject recipe specific parameters.

create game game_args='':
    game-engine --game={{game}} {{game_args}}

play-multiplayer game num_players: (create game "--players={{num_players}}")
    # run game-engine etc.

play-singleplayer game : (create game)
        # run game-engine etc.

I found that it kind of can be achieved with variadic parameters.

# extension to the example justfile
variadic-create game *game_args='':
    game-engine --game={{game}} {{game_args}}


play-multiplayer2 game num_players: (variadic-create game "--players="num_players)
    # run game-engine etc. 

However it puts an additional space character in the output which is not tolerated for my use case.

just play-multiplayer2 "ludo" 6
# output:
game-engine "ludo" --players= 6
                             ^------------  unwanted space here

Is it possible to tell just to "pre-parse" and resolve parameters (as in "--player={{num_players}}") before calling the recipe dependency?

[casey]

You should be able to use arbitrary expressions in dependency arguments:

play-multiplayer game num_players: (create game "--players=" + num_players")

Although you might need parenthesis to avoid ambiguity:

play-multiplayer game num_players: (create game ("--players=" + num_players"))

Does that work?

[antis81]

Okay I didn't know about string concatenation is possible here. Yes it works thank you!

[casey]

Nice, glad to hear!