look at @ the point creation method is sped up using an optional primitive call.

@ y "Primitive. Answer a Point whose x value is the receiver and whose y value is the argument. Optional. No Lookup. See Object documentation whatIsAPrimitive."

    <primitive: 18>
    ^Point x: self y: y

(a) Time millisecondsToRun:[50000 timesRepeat: [1@1]] -> 12

then I commentet the primitive call to see the diffirence in Number>>@ and I saw no difference... so I put a self halt in @

and the method isn't stopped when I redo (a).

but if I do that in a worspace:

|a| a := 1. self halt. Time millisecondsToRun:[50000 timesRepeat: [1@(a+1)]].

It stops and then the halt in #@ works ok ...

any idea of what I did wrong ?

Thanks Cédrick

really thanks Bert ;) clear explanation... I had dome vague ideas but thats far clearer now

A module is written in C (though often the C code is generated from

Squeak code) and needs to be compiled with a C compiler. Some modules are linked into the VM, some are external. You can list all currently used modules using "Smalltalk listLoadedModules".

SmalltalkImage current listLoadedModules for me on 3.9

To access a function from a C library without the need to write a

module, we have FFI primitives:

    puts: aString
            <cdecl: void 'puts' (char*) module: 'libSystem.dylib'>
            ^ExternalFunction externalCallFailed

When called, FFI looks up the function "puts" in "libSystem.dylib", converts the Smalltalk string to a C char*, and calls the function with it. This is for Mac OS X, on Linux, you would use "libc.so.1" and on Windows, I don't know, maybe "system32.dll" - FFI calls are very platform-specific. Also, they can crash Squeak easily. That's the reason the basic Squeak system does not use FFI at all, it is used for specific applications only, which have to deal with the platform issues.

ok :)

So primitives generally are the gateway to the world outside Smalltalk's

objects.

Additionally, some primitives are optional, they are only used to speed up lengthy computations. Like searching in a string or adding large numbers (ever tried "1000 factorial" ?).

yes :) thought it was 100% object power . A bit dissapointed ;)

euhh actually, I don't see any primitive call in Integer>>factorial , only a recursive function... did I miss somrthing ?

Integer>>factorial "Answer the factorial of the receiver."

self = 0 ifTrue: [^ 1]. self > 0 ifTrue: [^ self * (self - 1) factorial]. self error: 'Not valid for negative integers'

Thanks again Bert

Cédrick

ps: Considering pragma, is there any classical uses that can be interesting to do to work at the meta level... like Id' like to tag instance variables according to their meaning in my application. I have no idea on how to use pragma for that...

Pragmas *may* only be implemented for methods. It seems to be the case in Visual Works. Do you want an explanation for methods ?

yes if you can :) beacause I use getters and setters for my iv :)

Thanks

Cédrick

Symbol>>isDescriptionSelector "Answer wheter the receiver is a method selector following the naming conventions of a description selector." ^ self ~= #description and: [ self beginsWith: #description ]

This is a solution. But sometime, you would like to start a method with 'description' and this should not be a description method (or you do it by mistake).

Pragmas can be used to solve this problem. You then will annotate your method to tell the system that this methods are description methods. You do it like this:

MyObject class>>firstName

<description> ^ MAStringDescription auto: 'firstName' label: 'First name'

yes that's why I fiind that interesting.. clearer

Then, when you want to collect all the description methods in a class, you will use the methods in the protocol 'finding' of the Pragma class (class side).

Pragma allNamed: #description in: yourObject class

This returns a collection of Pragmas (compiled methods, selector and class) in which the pragma #description has been used in the class of yourObject.

this is cool ;) I'm manipulating them a bit right now

Is it clear ?

yes more thanks ;)

...

beacause I use getters and setters for my iv :)

And pragmas won't help you in my opinion, I don't see any relation :-) Why don't you want getters and setters ?

yes I wasn't clear. But as accesors are methods, I can use pragma to tag indirectly my instance variable. Just an idea of somethink that can be useful to me. I trying to make a kind of (small) knowledge management system, maybe more a kind of case based reasoning tool (ie. entities are composed of attributes or descriptors upon which the system reason..) and one simple solution for me is to directly use instance variables for these descriptors (and then I can tag to process them)...

I'm trying to see all kind of solution I could choose... even if right now I'm more trying to use dedicated Descriptor class...

I think one of the limitation I have (but I'll probably open a post on that one day) is that I need attributes as first-class entities and instance variable are not (are they ?)

Hope this is your last question of the day, I already answered 4 of them and I'm tired now :-D

this was ;) I have days like that :d

Squeak REALLY rocks

Cédrick

Am 21.08.2006 um 15:59 schrieb cdrick:

euhh actually, I don't see any primitive call in Integer>>factorial , only a recursive function... did I miss somrthing ?

No, #factorial is a regular method, but LargeInteger arithmetics is accelerated by LargeIntegerPlugin. You could try

[10000 factorial] timeToRun

with and without the primitives.

- Bert -