[REBOL] Re: file bug?
From: rotenca:telvia:it at: 9-May-2003 22:08
Hi Hugues,
1) Rebol data are stored in memory with an unknown format.
2) When you save a block or mold a block, all values in memory are converted
in a string (serialized).
3) This kind of string can be interpreted by the function Load (and Do) to
convert the string in a sequence of Rebol values in memory.
> when i do this :
> >> load "%s%40a"
> == %[s--a]
>
> I get the evaluation of the string, which is converted to a file datatype.
When Load find in a string datatype a sequence of byte which starts with %,
Load tries to convert it in a file datatype!
Every %xx sequence is interpreted like a single char where xx is the hex
number representation.
> when i do this:
> >> load %s%40a
> == [l1: 1
> l2: 2
> l3: 3
> l4: 4
> l5: 5
> ]
>
> I get the content of the file.
When you pass a file datatype (not a string datatype), Load read the file and
tries to interpret its content like a string.
> when i do this
> >> load %[s--a]
> ** Syntax Error: Invalid email -- %[s--a]
> ** Near: (line 1) load %[s--a]
>
> I get an email address evaluation, when i want a file.
You must think that when you type a sequence of chars in the console, you are
writing a string which is auto-magically loaded and then interpreted, so:
>>Load %[s--a]
must be seen like a sort of:
do load "Load %[s--a]"
The first Load interprets the string "Load %[s--a]" and finds in it a word:
load
and then the sequence:
%[s--a]
because this sequence does not start with " or { and contains the char @,
Rebol interprets it like an email address. We could say that email has
precedence on file. Load tries to create now a small Rebol program:
symbol datatype!
Load word!
%[s--a] email!
but %[s--a] is an invalid email symbol -> error!
If you want a file name with a @ in it, you can use "":
>> type? %"[s--a]"
== file!
or %40
>> type? probe %s%40a
%[s--a]
== file!
> >> load %sa.txt
> ** Access Error: Cannot open /c/rebol/view/sa.txt
> ** Where: halt-view
> ** Near: load %sa.txt
>
> I get an error because te file does not exist. So the word %sa.txt as been
> evaluated to a file!
yes, because it does not contain @ and starts with %
> So, what i know of rebol is that it evaluates the words. the load command
> needs either a file, or a url or a string. And in the rebol documentation
> i've read that the files are recognized by a percent just before the path of
> the file.
> What i don't understand is why the part just after the percent is evaluated
> whereas it's just a path in the file syntax.
Because also email can have %xx sequences in it:
>> [%63arl--rebol--com]
== [carl--rebol--com]
>> type? [%63arl--rebol--com]
== email!
> Another thing :
> when i do this :
> >> do %sa
> ** Syntax Error: Script is missing a REBOL header
> ** Where: halt-view
> ** Near: do %sa
> I get an error because rebol want a script, but the %sa has been evaluated a
> a file.
No, because exists a file in your current dir called "sa" which does not
contain a standard rebol header (Rebol [])
Hope it helps. (my English is bad)
---
Ciao
Romano
