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# Description This PR adds lazy closure evaluation to the `default` command (closes #14160). - For non-closure values and without providing a column name, `default` acts the same as before - The user can now provide multiple column names to populate if empty - If the user provides a column name, the input must be a record or list, otherwise an error is created. - The user can now provide a closure as a default value - This closure is run without any arguments or input - The closure is never evaluated if the value isn't needed - Even when column names are supplied, the closure is only run once (and cached to prevent re-calling it) For example: ```nushell > default { 1 + 2 } # => 3 > null | default 3 a # => previously `null`, now errors > 1 | default { sleep 5sec; 3 } # => `1`, without waiting 5 seconds > let optional_var = null; $optional_var | default { input 'Enter value: ' } # => Returns user input > 5 | default { input 'Enter value: ' } # => `5`, without prompting user > ls | default { sleep 5sec; 'N/A' } name # => No-op since `name` column is never empty > ls | default { sleep 5sec; 'N/A' } foo bar # => creates columns `foo` and `bar`; only takes 5 seconds since closure result is cached # Old behavior is the same > [] | default 'foo' # => [] > [] | default --empty 'foo' # => 'foo' > default 5 # => 5 ``` # User-Facing Changes - Users can add default values to multiple columns now. - Users can now use closures as the default value passed to `default`. - To return a closure, the user must wrap the closure they want to return inside another closure, which will be run (`default { $my_closure }`). # Tests + Formatting All tests pass. # After Submitting --------- Co-authored-by: 132ikl <132@ikl.sh> |
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This crate contains the majority of our commands
We allow ourselves to move some of the commands in nu-command to nu-cmd-* crates as needed.
Internal Nushell crate
This crate implements components of Nushell and is not designed to support plugin authors or other users directly.