add-path, rm-path

add-path, rm-path

[Deliverable Mail]

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Many people have python-esque scripts which add a path to a PATH-like
variable only if it's not there already, or remove it from there completely.
I wonder whether zsh has it embedded?
 Cheers,
Alexy

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Re: add-path, rm-path

[Bart Schaefer]

On Sep 28,  3:16pm, Deliverable Mail wrote:
} 
} Many people have python-esque scripts which add a path to a PATH-like
} variable only if it's not there already, or remove it from there completely.
} I wonder whether zsh has it embedded?

Zsh has three components that together accomplish this.  The first is
automatic linkage between arrays and colon-separated scalars, in this
case the array "path" and the scalar "PATH".

The second is "typeset -U" for creating self-uniquifying arrays.

The third is ${array:#pattern} for removing elements matching a pattern
from an array.

The only time you need a function is when you want to control the order
in which the single remaining instance of a duplicated element appears
in the array, after de-duping.  The "typeset -U" behavior is to keep
the one with the lowest array index, even if that means inserting a new
element and deleting an existing equivalent one.

Re: add-path, rm-path

[Deliverable Mail]

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I must say I'm impressed even more with zsh. So far it has absolutely
everything imaginable! Thanks for all the fish. :)
 Cheers,
Alexy
 On 9/28/05, Bart Schaefer <schaefer@brasslantern.com> wrote:
>
> On Sep 28, 3:16pm, Deliverable Mail wrote:
> }
> } Many people have python-esque scripts which add a path to a PATH-like
> } variable only if it's not there already, or remove it from there
> completely.
> } I wonder whether zsh has it embedded?
>
> Zsh has three components that together accomplish this. The first is
> automatic linkage between arrays and colon-separated scalars, in this
> case the array "path" and the scalar "PATH".
>
> The second is "typeset -U" for creating self-uniquifying arrays.
>
> The third is ${array:#pattern} for removing elements matching a pattern
> from an array.
>
> The only time you need a function is when you want to control the order
> in which the single remaining instance of a duplicated element appears
> in the array, after de-duping. The "typeset -U" behavior is to keep
> the one with the lowest array index, even if that means inserting a new
> element and deleting an existing equivalent one.
>

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