World: r3wp
[Core] Discuss core issues
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| Chris 17-Jan-2007 [6748x6] | uses: func [args [block!] spec [block!][
args: context args
func [options [block!] compose/only [
options: make (args) options
do bind (spec) in options 'self
]
]
|
Usage: >> f: uses [x: y: 1][print y] >> f [] 1 >> f [y: 2] 2 | |
Although arguments for any 'uses based functions must be contained in a block, it does allow for optional arguments with preset values. | |
Any suggestions/bugs? | |
Hmm, lost a close bracket in a VNC post... | |
uses: func [args [block!] spec [block!]][
args: context args
func [options [block!]] compose/only [
options: make (args) options
do bind (spec) in options 'self
]
]
| |
| Ladislav 17-Jan-2007 [6754] | does anybody know if there is any difference between negate bitset and complement bitset ? |
| Gabriele 17-Jan-2007 [6755] | i think they are the same. |
| Anton 17-Jan-2007 [6756] | That looks pretty good, Chris. Can you post any examples where you used it ? |
| Volker 17-Jan-2007 [6757] | how about locals too? then you have closures. And itdoes not work recursively, how about copying the body when binding? |
| Anton 17-Jan-2007 [6758] | Locals ? You can have as many locals as you want in the args block. |
| Volker 17-Jan-2007 [6759] | true, everything is optional. late here^^ |
| Maxim 17-Jan-2007 [6760] | a part for a little bit of excentricity on your part... do the trailing ^^ you add on most/all post mean something I have been missing? |
| Chris 17-Jan-2007 [6761x4] | Anton, I don't have any good samples at the moment -- it's part of an unfinished project. I'll try and come up with some based on the usage requirements I have. |
I see it mostly as an alterate way of writing functions that would otherwise require many refinements. The benefit being neater presentation. | |
print-cgi: uses [
status: 200
type: 'text/plain
content: ""
location: %/
][
print switch status [
200 [rejoin ["Content-Type: " type "^/^/" content]]
302 [join "Status: 302^/Location: " location]
]
]
print-cgi [content: "Text"]
print-cgi [type: 'text/html content: "<html>Text</html>"]
print-cgi [status: 302 location: http://www.rebol.net/]
| |
A quickie example, but illustrates the flexibility and readability. | |
| Anton 18-Jan-2007 [6765] | Nice one. |
| PeterWood 18-Jan-2007 [6766x3] | Ladislav: -16:00 to +15:45 is more than enough according to Wikipedia Because the earliest and latest time zones are 26 hours apart, any given calendar date exists at some point on the globe for 50 hours. For example, April 11 begins in time zone UTC+14 at 10:00 UTC April 10, and ends in time zone UTC-12 at 12:00 UTC April 12. Full story at http://en.wikipedia.org/wiki/Timezones |
And a list of all the current (and a few old ones) at http://en.wikipedia.org/wiki/UTC%2B0 | |
UTC-0:25 was used in Ireland as Dublin Mean Time. In 1916 the time was changed to GMT. (Thankfully!) | |
| Ladislav 18-Jan-2007 [6769] | :-D |
| Oldes 19-Jan-2007 [6770] | I have a question, I have this code: >> b: "1234str" ri: func[b /local i][i: copy/part b 4 b: skip b 4 i] probe ri b probe b 1234 1234str Why the b string is not "str" ? |
| Cyphre 19-Jan-2007 [6771] | Here is the explanation: >> a: "1234" == "1234" >> b: a == "1234" >> b: skip b 2 == "34" >> a == "1234" >> b == "34" >> |
| Ladislav 19-Jan-2007 [6772x3] | ...because the index attribute of REBOL series is not volatile. |
Cyphre - I doubt this explains it | |
correction : the index attribute of REBOL any-blocks and any-strings is not volatile | |
| Oldes 19-Jan-2007 [6775] | Ok, so how should I write the code, which will eat the 4 chars and change the position if I don't want to return the new b from the function |
| Ladislav 19-Jan-2007 [6776] | as I said: you cannot change the index of a series, so the only possibility is to share the variable |
| Cyphre 19-Jan-2007 [6777] | Ladislav, I though the 'b in function 'ri is different from the 'b in global context so that's why the index differs. |
| Ladislav 19-Jan-2007 [6778] | actually the error lies in the fact, that many users think, that SKIP changes the index of a series. It actually doesn't: b: "1234" index? skip b 2 ; == 3 index? b ; == 1 |
| Oldes 19-Jan-2007 [6779] | but than it's quite useless... I wanted to do a function read-integer buffer and etc. and make it universal:( I know, I can set buffer as global variable (or in the context) and do just read-integer etc. |
| Ladislav 19-Jan-2007 [6780x3] | you don't have to, the following works too: |
ri: func [b [word!] /local i] [i: copy/part get b 4 set b skip get b 4 i] | |
b: "1234str" probe ri 'b | |
| Oldes 19-Jan-2007 [6783] | yes, that's it, thanks:-) |
| Ladislav 19-Jan-2007 [6784] | sorry, Cyphre, it looks that my explanation is exactly the same as yours :-) |
| Oldes 19-Jan-2007 [6785x2] | anyway, it looks, it would be better to use some version with the buffer as variable in the context:( |
isn't it too many operations to just get a string?
read-str: func[b [word!] /local s nb][
s: none
nb: get b
error? try [
i: index? nb
s: copy/part nb i: (index? find nb #{00}) - i
set b skip nb (i + 1)
]
s
]
| |
| PeterWood 19-Jan-2007 [6787x2] | If by '"eat " you mean permanently remove then : b: remove/part b 4 |
As a function: >> b: "1234str" == "1234str" >> ri: func[b] [b: remove/part b 4] >> probe ri b str == "str" >> probe head b str | |
| Oldes 19-Jan-2007 [6789] | rather not to remove, just skip:-) |
| Anton 19-Jan-2007 [6790] | Oldes, you don't need to s: none S is a local and locals are automatically set to NONE for you. (Unless you are using a very old rebol.) |
| Oldes 19-Jan-2007 [6791] | that's true:-) |
| Anton 19-Jan-2007 [6792x3] | This is how I would do it. |
read-str: func[buf [word!] /local result pos][
if pos: find get buf #{00} [
result: copy/part get buf pos
set buf next pos
]
result
]
| |
>> my-string: #{11221122003344334400}
== #{11221122003344334400}
>> print mold read-str 'my-string
#{11221122}
>> print mold my-string
#{3344334400}
>> print mold read-str 'my-string
#{33443344}
>> print mold my-string
#{}
| |
| Oldes 19-Jan-2007 [6795] | That looks much more better, thanks:-) |
| Ladislav 20-Jan-2007 [6796] | add 0.0.1 0.0.255 ; == 0.0.255 looks rather surprising to me. any opinions? |
| Volker 20-Jan-2007 [6797] | makes sense when used with colors |
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