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The Inbox: Environments-cmm.57.mcz

Chris Muller uploaded a new version of Environments to project The Inbox:
http://source.squeak.org/inbox/Environments-cmm.57.mcz

==================== Summary ====================

Name: Environments-cmm.57
Author: cmm
Time: 23 March 2015, 1:58:37.126 pm
UUID: 6e10d99c-b424-4f94-9152-18ccd72ca623
Ancestors: Environments-topa.56

Fix access to globals which were defined by: Smalltalk at: #MyGlobal ifAbsentPut: [myValue].

=============== Diff against Environments-topa.56 ===============

Item was changed:
----- Method: Environment>>at:ifAbsentPut: (in category 'emulating') -----
+ at: aSymbol ifAbsentPut: aBlock
- at: aSymbol ifAbsentPut: aBlock
^ declarations
at: aSymbol
+ ifAbsentPut:
+ [ bindings
+ at: aSymbol
+ ifAbsentPut: aBlock ]!
- ifAbsentPut: aBlock!

Chris Muller-3

Re: The Inbox: Environments-cmm.57.mcz

To define a global variable in code, while taking care not to
over-write it if it already is defined, I wrote:

Smalltalk at: #MyGlobal ifAbsentPut: [myValue].

But this only put it in the Smalltalk environments 'declarations', not
its 'bindings', which renders MyGlobal inaccessible from any code.

I don't really like this nesting of at:ifAbsentPut: into 'bindings',
but it does solve the bug for the basic case. Is it the right way to
fix it?

On Mon, Mar 23, 2015 at 1:58 PM, <[hidden email]> wrote:

> Chris Muller uploaded a new version of Environments to project The Inbox:
> http://source.squeak.org/inbox/Environments-cmm.57.mcz
>
> ==================== Summary ====================
>
> Name: Environments-cmm.57
> Author: cmm
> Time: 23 March 2015, 1:58:37.126 pm
> UUID: 6e10d99c-b424-4f94-9152-18ccd72ca623
> Ancestors: Environments-topa.56
>
> Fix access to globals which were defined by: Smalltalk at: #MyGlobal ifAbsentPut: [myValue].
>
> =============== Diff against Environments-topa.56 ===============
>
> Item was changed:
> ----- Method: Environment>>at:ifAbsentPut: (in category 'emulating') -----
> + at: aSymbol ifAbsentPut: aBlock
> - at: aSymbol ifAbsentPut: aBlock
> ^ declarations
> at: aSymbol
> + ifAbsentPut:
> + [ bindings
> + at: aSymbol
> + ifAbsentPut: aBlock ]!
> - ifAbsentPut: aBlock!
>
>

Levente Uzonyi-2

Re: The Inbox: Environments-cmm.57.mcz

On Mon, 23 Mar 2015, Chris Muller wrote:

> To define a global variable in code, while taking care not to
> over-write it if it already is defined, I wrote:
>
> Smalltalk at: #MyGlobal ifAbsentPut: [myValue].
>
> But this only put it in the Smalltalk environments 'declarations', not
> its 'bindings', which renders MyGlobal inaccessible from any code.
>
> I don't really like this nesting of at:ifAbsentPut: into 'bindings',
> but it does solve the bug for the basic case. Is it the right way to
> fix it?

No, it's a hack. The right way to do it is to use #bind:to: to create a
new binding. Something like this should work:

at: aSymbol ifAbsentPut: aBlock

^self at: aSymbol ifAbsent: [
self at: aSymbol put: aBlock value ]

Levente

>
> On Mon, Mar 23, 2015 at 1:58 PM, <[hidden email]> wrote:
>> Chris Muller uploaded a new version of Environments to project The Inbox:
>> http://source.squeak.org/inbox/Environments-cmm.57.mcz
>>
>> ==================== Summary ====================
>>
>> Name: Environments-cmm.57
>> Author: cmm
>> Time: 23 March 2015, 1:58:37.126 pm
>> UUID: 6e10d99c-b424-4f94-9152-18ccd72ca623
>> Ancestors: Environments-topa.56
>>
>> Fix access to globals which were defined by: Smalltalk at: #MyGlobal ifAbsentPut: [myValue].
>>
>> =============== Diff against Environments-topa.56 ===============
>>
>> Item was changed:
>> ----- Method: Environment>>at:ifAbsentPut: (in category 'emulating') -----
>> + at: aSymbol ifAbsentPut: aBlock
>> - at: aSymbol ifAbsentPut: aBlock
>> ^ declarations
>> at: aSymbol
>> + ifAbsentPut:
>> + [ bindings
>> + at: aSymbol
>> + ifAbsentPut: aBlock ]!
>> - ifAbsentPut: aBlock!
>>
>>
>
>

marcel.taeumel (old)

Re: The Inbox: Environments-cmm.57.mcz

My mental model of "Smalltalk" is that there is all global stuff stored: classes and other global variables such as ActiveWorld and ActiveHand. As Smalltalk >> #at: returns the object behind that global name and Smalltalk >> #at:put: overwrites such a global binding with a new object, this looks like a regular dictionary to me. Having this, #at:ifAbsentPut: should just combine #at: and #at:put: -- like Levente proposed.

What is the current state of our discussion about Smalltalk offering the full Dictionary interface?

Best,
Marcel

Bert Freudenberg

Re: The Inbox: Environments-cmm.57.mcz

In reply to this post by Levente Uzonyi-2

> On 24.03.2015, at 04:22, Levente Uzonyi <[hidden email]> wrote:
>
> On Mon, 23 Mar 2015, Chris Muller wrote:
>
>> To define a global variable in code, while taking care not to
>> over-write it if it already is defined, I wrote:
>>
>> Smalltalk at: #MyGlobal ifAbsentPut: [myValue].
>>
>> But this only put it in the Smalltalk environments 'declarations', not
>> its 'bindings', which renders MyGlobal inaccessible from any code.
>>
>> I don't really like this nesting of at:ifAbsentPut: into 'bindings',
>> but it does solve the bug for the basic case. Is it the right way to
>> fix it?
>
> No, it's a hack. The right way to do it is to use #bind:to: to create a new binding. Something like this should work:
>
> at: aSymbol ifAbsentPut: aBlock
>
> ^self at: aSymbol ifAbsent: [
> self at: aSymbol put: aBlock value ]
>
> Levente

+1

I just ran into this too ...

- Bert -

smime.p7s (5K) Download Attachment

Chris Muller-4

Re: The Inbox: Environments-cmm.57.mcz

In reply to this post by Levente Uzonyi-2

Oh that is so much better; use the existing API's which we know work
rather than another path through the code which modifies the state of
the object.

I just tried it and it worked, thanks Levente! I'll commit it to trunk.

On Mon, Mar 23, 2015 at 10:22 PM, Levente Uzonyi <[hidden email]> wrote:

> On Mon, 23 Mar 2015, Chris Muller wrote:
>
>> To define a global variable in code, while taking care not to
>> over-write it if it already is defined, I wrote:
>>
>> Smalltalk at: #MyGlobal ifAbsentPut: [myValue].
>>
>> But this only put it in the Smalltalk environments 'declarations', not
>> its 'bindings', which renders MyGlobal inaccessible from any code.
>>
>> I don't really like this nesting of at:ifAbsentPut: into 'bindings',
>> but it does solve the bug for the basic case. Is it the right way to
>> fix it?
>
>
> No, it's a hack. The right way to do it is to use #bind:to: to create a new
> binding. Something like this should work:
>
> at: aSymbol ifAbsentPut: aBlock
>
> ^self at: aSymbol ifAbsent: [
> self at: aSymbol put: aBlock value ]
>
> Levente
>
>>
>> On Mon, Mar 23, 2015 at 1:58 PM, <[hidden email]> wrote:
>>>
>>> Chris Muller uploaded a new version of Environments to project The Inbox:
>>> http://source.squeak.org/inbox/Environments-cmm.57.mcz
>>>
>>> ==================== Summary ====================
>>>
>>> Name: Environments-cmm.57
>>> Author: cmm
>>> Time: 23 March 2015, 1:58:37.126 pm
>>> UUID: 6e10d99c-b424-4f94-9152-18ccd72ca623
>>> Ancestors: Environments-topa.56
>>>
>>> Fix access to globals which were defined by: Smalltalk at: #MyGlobal
>>> ifAbsentPut: [myValue].
>>>
>>> =============== Diff against Environments-topa.56 ===============
>>>
>>> Item was changed:
>>> ----- Method: Environment>>at:ifAbsentPut: (in category 'emulating')
>>> -----
>>> + at: aSymbol ifAbsentPut: aBlock
>>> - at: aSymbol ifAbsentPut: aBlock
>>> ^ declarations
>>> at: aSymbol
>>> + ifAbsentPut:
>>> + [ bindings
>>> + at: aSymbol
>>> + ifAbsentPut: aBlock ]!
>>> - ifAbsentPut: aBlock!
>>>
>>>
>>
>>
>