[REBOL] Re: About Standards and Best Practices
From: reboler:bol at: 3-Sep-2003 17:31
Hi Folks!,
Thanks to all of you. Elan, Greg, Ashley and Andrew.
These are real good tips that makes me change the way I was programming.
Other things I think should be interesting is the benchmark of functions..
a) conditional loops.. 'repeat instead of 'foreach, 'forall instead of
'foreach.;
b) parse or load/markup (if using parse is faster than 'load/markup.
You know, things like that. ok.
Thank you again.
Best regards,
-DJ
----- Original Message -----
From: "Elan" <[rebol--techscribe--com]>
To: <[rebol-list--rebol--com]>
Sent: Wednesday, September 03, 2003 1:25 PM
Subject: [REBOL] Re: About Standards and Best Practices
> Hi.
>
> Another issue that comes to mind is name space and side effects. If a
> function introduces a word that will be used within the context of that
> function only, then that word should be declared local to the function
> in order to avoid name clashes that may result in unexpected side effects:
>
> f: func [ /local word] [
> word: "function's local word."
> ]
>
> This prevents errors that result from setting a global word to some value,
then evaluating a function that happens to set the same word locally to a
different value, and then continuing to use the global word. This is
especially critical if functions are reused either by their original author
or by some unsuspecting consumer. Example:
> ;--- consumer's script
> REBOL []
>
> ;- globally declared word
> erase-harddrive-completely?: NO
>
> ;- evaluating function from a downloaded library
>
> do %down-loaded-library ;- contains function list-directory
>
> this-dir-contents: list-directory
> .
> .
> .
> if erase-harddrive-completely? [ erase-harddrive-completely ]
>
> ;--- end user's script
>
> So, what's the problem? Imagine the function "borrowed" from the
downloaded library looks like this:
> ;--- function in downloaded library --
> list-directory: func [ /interactive ] [
> erase-harddrive-completely?: "No"
> directory-listing: read %.
> if interactive [
> display-directory-listing
> erase-harddrive-completely?: ask "Should I erase the hard drive
completely?"
> ]
> directory-listing
> ];---- end libraray function ----
>
> Note that the user's script sets erase-harddrive-completely? to the logic!
value No, whereas the function sets the word erase-harddrive-completely? to
the string! "No". The string! "No", however, evaluates as a logic! True:
