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World: r3wp

[Core] Discuss core issues

[unknown: 5]
18-Dec-2008
[11682x2]
it is like /direct
difference is that the index stays at head as you reference it.
BrianH
18-Dec-2008
[11684]
How often do you need to do these reads, and can they be sorted in 
batches?
[unknown: 5]
18-Dec-2008
[11685]
They do get sorted but they are done often and the batch sort is 
random sized depending on the request
BrianH
18-Dec-2008
[11686]
You are using variable-length records rather than fixed length?
[unknown: 5]
18-Dec-2008
[11687x2]
yes ;-)
Your wondering how right?
BrianH
18-Dec-2008
[11689]
That is a lot slower. I am not wondering how, I've followed the discussions 
in your group.
[unknown: 5]
18-Dec-2008
[11690]
slower than what?
BrianH
18-Dec-2008
[11691]
Fixed length. Databases usually work in increments of disk pages 
because it is faster.
[unknown: 5]
18-Dec-2008
[11692x2]
But at a cost
What if declared a field varchar[2000] and you only populate it with 
50?
BrianH
18-Dec-2008
[11694]
Varchars are slower in practice. You can minimize the overhead of 
disk page access by packing pages if you have to. The OS reads in 
pages anyways.
[unknown: 5]
18-Dec-2008
[11695]
I have minimized it to a greater extent.
BrianH
18-Dec-2008
[11696]
A read of less than 1 disk page is just as slow as a read of 1 disk 
page.
[unknown: 5]
18-Dec-2008
[11697]
I'm hitting you privately.
BrianH
18-Dec-2008
[11698]
Ouch :)
Steeve
18-Dec-2008
[11699x2]
say Oooooo to relax your sphincter muscles Brian
forget that
Chris
19-Dec-2008
[11701x3]
A 'bind question: how do I construct an object containing blocks 
without changing the blocks' contexts?  This bad:

>> id: #foo
== #foo
>> blk: [id]
== [id]
>> reduce blk
== [#foo]
>> ctx: context append/only [id: #bar bk:] blk
>> reduce ctx/bk
== [#bar]

This good:

>> id: #foo
== #foo
>> blk: [id]
== [id]
>> reduce blk
== [#foo]
>> ctx: magic-context append/only [id: #bar bk:] blk
>> reduce ctx/bk
== [#foo]

How to 'magic-context ?
Ugly answer:

magic-context: func [blk [block!] /local out][
	out: context join extract blk 2 [none]
	set out
 extract/index blk 2 2
]
I was hoping 'construct would do it, but alas not.
Ammon
19-Dec-2008
[11704]
>> ctx: context append/only [id: #bar blk:] reduce blk
>> ctx/blk
== [#foo]
[unknown: 5]
20-Dec-2008
[11705x3]
What is the best way to set all locals in a function to none before 
returning the result of the function if you have an extensive list 
of locals?
Myself I think that should be the default behavior.
I know for recursive operations that may not be desireable but I 
think they could introduce maybe another feature that allows certain 
ones to not be cleared.  For example, add an exclude native to the 
system to exclude the clearing of certain locals.
Geomol
20-Dec-2008
[11708]
Is there a better way than just doing:

var1: var2: var3: ... varN: none
[unknown: 5]
20-Dec-2008
[11709x2]
Well if you got say 15 or more it just looks ugly.
would be nice if you could  just have a command  inside your function 
that says  clear-locals.
Geomol
20-Dec-2008
[11711]
That would require to get access to locals from the outside of a 
function. I'm not away of a way to do that.
[unknown: 5]
20-Dec-2008
[11712]
I don't think so if it could be bound inside the calling function.
Geomol
20-Dec-2008
[11713x2]
*aware* of a way ...
You still need to get easy access to all the locals. Like having 
them in a series.
Sunanda
20-Dec-2008
[11715]
If you know the "name" of the function, then you can get at the variables:
f: func [a b /local c d e] [print mold first :f]
f 1 2
Then you could run a loop for all those after /local
Geomol
20-Dec-2008
[11716]
Ah, that's right! :-)
Gregg
20-Dec-2008
[11717]
1) what is the purpose of clearing the locals?

2) how often do you need to do this, where the list is large? i.e. 
does it indicate a design issue?
[unknown: 5]
20-Dec-2008
[11718x4]
I tried  that after I posted Sunanda but even though I could get 
to them I was still able to out put a value of the local before setting 
them to none that way so what that  meant was that even though I 
attempted to set them to none! that way that it didn't take (and 
didn't give me an error either).
Gregg, to reduce memory overhead and allow the garbage collector 
to give back some memory.
Gregg, I don't think your second question matters to me.  What matters 
is efficiency to me.
Sundanda , here is a test:
Geomol
20-Dec-2008
[11722]
I found a way to set all locals to none, while just specifying one 
of the locals, and it isn't beautiful, I'm afraid:

f: func [/local a b c][
	a: 1 b: 2 c: 3
	print [a b c]

	; This next line set all locals to none:
	set next bind first :f 'a none
	print [a b c]
]

Running the function in the console:
>> f
1 2 3
none none none
>>
[unknown: 5]
20-Dec-2008
[11723x4]
myfunc: func [ /local lcl lcl2][
    lcl: "I still have a value"
    print mold lcl2: next find third get 'myfunc /local
    foreach item lcl2 [print mold item]
    foreach item lcl2 [print mold get :item]
    foreach item lcl2 [set :item none!]
    print lcl
]
Grrr, I see something I did wrong in my test.
myfunc: func [ /local lcl lcl2][
    lcl: "I still have a value"
    print mold lcl2: next find third get 'myfunc /local
    foreach item lcl2 [print mold item]
    foreach item lcl2 [print mold get :item]
    foreach item lcl2 [set :item none]
    print lcl
]
Yeah John, that is the way I think it has to be done by using 'bind.
Geomol
20-Dec-2008
[11727]
My example only works for functions, which doesn't take arguments. 
If a function take argument, you need:

f: func [v /local a b c][
	a: 1 b: 2 c: 3
	print [a b c]

	set next find bind first :f 'a /local none
	print [a b c]
]
[unknown: 5]
20-Dec-2008
[11728]
right
Geomol
20-Dec-2008
[11729]
Hard to read that setting-to-none line, and I haven't found a way 
to do it by a function call (like a clear-locals function).
[unknown: 5]
20-Dec-2008
[11730]
Its a good idea though - isn't it?
Geomol
20-Dec-2008
[11731]
Yes, a native clear-locals seem like a good idea.