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SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

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Nicolai Hess

SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

The following method compiles with Opal:

createRedMorph
^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.

Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would

a search expression look, for finding code like:

"(some expression);yourself"

nicolai

Sven Van Caekenberghe-2

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

Interesting.

I think that for a cascade you need more than one message send.

> On 16 Sep 2015, at 10:56, Nicolai Hess <[hidden email]> wrote:
>
> The following method compiles with Opal:
>
> createRedMorph
> ^ (self new color:Color red); yourself
>
> but gives a syntax error with the old compilers parser
>
> createRedMorph
> ^ (self new color:Color red)End of block expected -> ; yourself
>
>
> removing the parenthesis of course works for both.
> Who is right ?
>
>
> (for those who understand the ParseTreeSearcher syntax, how would
> a search expression look, for finding code like:
>
> "(some expression);yourself"
>
>
> nicolai
>

Thierry Goubier

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

In reply to this post by Nicolai Hess

Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph

^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new

color: Color red;

yourself

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:

The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Nicolai Hess

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

There are currently two methods in Pharo 5.0 with this

syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:

Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Nicolai Hess

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

Arrg, sorry Yuri, this (too) isn't from QualityAssistance, but DependencyAnalyzer

2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:

OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Thierry Goubier

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

In reply to this post by Nicolai Hess

2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:

OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

But

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Thierry Goubier

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

Argh, sent too early:

self new color: Color red; yourself

est bien une cascade, non?

Thierry

2015-09-16 15:12 GMT+02:00 Thierry Goubier <[hidden email]>:

2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:
OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

But

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

demarey

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

In reply to this post by Nicolai Hess

The PackageAnalyzer is now maintained by me (especially because it is so usefull for the bootstrap).

I just fixed that.

Indeed, the code was wrong.

Christophe

Le 16 sept. 2015 à 15:05, Nicolai Hess a écrit :

OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

smime.p7s (5K) Download Attachment

Ben Coman

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

In reply to this post by Nicolai Hess

On Wed, Sep 16, 2015 at 4:56 PM, Nicolai Hess <[hidden email]> wrote:

> The following method compiles with Opal:
>
> createRedMorph
> ^ (self new color:Color red); yourself
>
> but gives a syntax error with the old compilers parser
>
> createRedMorph
> ^ (self new color:Color red)End of block expected -> ; yourself
>
>
> removing the parenthesis of course works for both.
> Who is right ?

What is the result in other dialects?
This is a potential incompatibility for little gain.
Anyway I would guess Opal is wrong.
cheers -ben

John Brant-2

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

On 9/16/2015 10:34 AM, Ben Coman wrote:

> On Wed, Sep 16, 2015 at 4:56 PM, Nicolai Hess <[hidden email]> wrote:
>> The following method compiles with Opal:
>>
>> createRedMorph
>> ^ (self new color:Color red); yourself
>>
>> but gives a syntax error with the old compilers parser
>>
>> createRedMorph
>> ^ (self new color:Color red)End of block expected -> ; yourself
>>
>>
>> removing the parenthesis of course works for both.
>> Who is right ?
>
> What is the result in other dialects?

Dolphin lets you do "self ; yourself" as well as the example above.
However, both VW & VA don't allow it.

> This is a potential incompatibility for little gain.
> Anyway I would guess Opal is wrong.

I don't remember if we allowed this on purpose to be compatible with
other Smalltalks or if it was a bug we missed. Anyway, a simple fix is
to add " and: [node parentheses isEmpty]" to the
RBParser>>parseCascadeMessage method:

parseCascadeMessage
| node receiver messages semicolons |
node := self parseKeywordMessage.
(currentToken isSpecial
and: [currentToken value = $; and: [node isMessage and: [node
parentheses isEmpty]]]) ifFalse: [^node].
...

John Brant

Nicolai Hess

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

2015-09-17 1:18 GMT+02:00 John Brant <[hidden email]>:

On 9/16/2015 10:34 AM, Ben Coman wrote:

On Wed, Sep 16, 2015 at 4:56 PM, Nicolai Hess <[hidden email]> wrote:

The following method compiles with Opal:

createRedMorph
^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

What is the result in other dialects?

Dolphin lets you do "self ; yourself" as well as the example above. However, both VW & VA don't allow it.

Thanks for the info.

This is a potential incompatibility for little gain.
Anyway I would guess Opal is wrong.

I don't remember if we allowed this on purpose to be compatible with other Smalltalks or if it was a bug we missed. Anyway, a simple fix is to add " and: [node parentheses isEmpty]" to the RBParser>>parseCascadeMessage method:

parseCascadeMessage
| node receiver messages semicolons |
node := self parseKeywordMessage.
(currentToken isSpecial
and: [currentToken value = $; and: [node isMessage and: [node parentheses isEmpty]]]) ifFalse: [^node].
...

John Brant

Nicolai Hess

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

In reply to this post by Thierry Goubier

2015-09-16 15:14 GMT+02:00 Thierry Goubier <[hidden email]>:

Argh, sent too early:

self new color: Color red; yourself

est bien une cascade, non?

Yes, but in

(self new color: Color red); yourself

the expression in parenthesis looks like "this evalulates first, to 'anObject' ", so we send " ; yourself",

a cascaded messages with only one message to "anObject".

Thierry

2015-09-16 15:12 GMT+02:00 Thierry Goubier <[hidden email]>:

2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:
OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

But

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Thierry Goubier

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

2015-09-17 9:10 GMT+02:00 Nicolai Hess <[hidden email]>:

2015-09-16 15:14 GMT+02:00 Thierry Goubier <[hidden email]>:
Argh, sent too early:

self new color: Color red; yourself

est bien une cascade, non?

Yes, but in

(self new color: Color red); yourself
the expression in parenthesis looks like "this evalulates first, to 'anObject' ", so we send " ; yourself",
a cascaded messages with only one message to "anObject".

Yes, agreed of course.

In a way, it looks like an error correction type of thing: the parser knows the parenthesis shouldn't be there or the ; shouldn't be there, so it chooses one interpretation out of the two: here it is the parenthesis are unnecessary.

By the way, John found another issue with a fix you did in RBParser (RBPatternParser>>parseUnaryMessage) which fail some refactoring expressions. Can you have a look?

Thierry

Thierry

2015-09-16 15:12 GMT+02:00 Thierry Goubier <[hidden email]>:

2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:
OK, I think Sven is right and a cascade needs at least one message send

"self ; yourself"

doesn't work too (both parser don't accept this).

But

There are currently two methods in Pharo 5.0 with this
syntax:

DAPackageAnalyzerWindow class>>#onPackagesNamed:
DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:

@Yuri, can you change that.

And I think we should fix RBParser.

2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
Nicolai,

can you try with the RBParser directly? I believe Opal uses the RBParser.

RBParser parseMethod: 'createRedMorph
    ^ (self new color:Color red); yourself'

Oh, RBParser sees it as:

self new
color: Color red;
yourself

:)

Thierry

2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
The following method compiles with Opal:

createRedMorph
    ^ (self new color:Color red); yourself

but gives a syntax error with the old compilers parser

createRedMorph
    ^ (self new color:Color red)End of block expected -> ; yourself

removing the parenthesis of course works for both.
Who is right ?

(for those who understand the ParseTreeSearcher syntax, how would
a search expression look, for finding code like:

   "(some expression);yourself"

nicolai

Sven Van Caekenberghe-2

Re: SyntaxError: parentheses; cascades and yourself (Opal vs. old compilers parser)

> On 17 Sep 2015, at 09:32, Thierry Goubier <[hidden email]> wrote:
>
>
>
> 2015-09-17 9:10 GMT+02:00 Nicolai Hess <[hidden email]>:
>
>
> 2015-09-16 15:14 GMT+02:00 Thierry Goubier <[hidden email]>:
> Argh, sent too early:
>
> self new color: Color red; yourself
>
> est bien une cascade, non?
>
> Yes, but in
>
> (self new color: Color red); yourself
> the expression in parenthesis looks like "this evalulates first, to 'anObject' ", so we send " ; yourself",
> a cascaded messages with only one message to "anObject".
>
> Yes, agreed of course.
>
> In a way, it looks like an error correction type of thing: the parser knows the parenthesis shouldn't be there or the ; shouldn't be there, so it chooses one interpretation out of the two: here it is the parenthesis are unnecessary.

Hmm, I don't agree.

We as humans can infer that, from a language/compiler's standpoint it is not clear/possible.

someObject message1; message2 is a pure cascade
(someObject message1) message2 is not a cascade, message2 being sent to the result

the last expression is totally equivalent to

someObject message1 message2

However

expression message
expression ; message

could be equivalent, like if it said

expression yourself; message

but the decision to drop the parenthesis cannot be made automatically, IMHO

I would make the spurious ; an error, to avoid confusion

> By the way, John found another issue with a fix you did in RBParser (RBPatternParser>>parseUnaryMessage) which fail some refactoring expressions. Can you have a look?
>
> Thierry
>
>
>
>
>
>
>
>
> Thierry
>
>
> 2015-09-16 15:12 GMT+02:00 Thierry Goubier <[hidden email]>:
>
>
> 2015-09-16 15:05 GMT+02:00 Nicolai Hess <[hidden email]>:
> OK, I think Sven is right and a cascade needs at least one message send
>
> "self ; yourself"
>
> doesn't work too (both parser don't accept this).
>
> But
>
>
>
> There are currently two methods in Pharo 5.0 with this
> syntax:
>
> DAPackageAnalyzerWindow class>>#onPackagesNamed:
> DAPackageCycleDetectionTreeModel class>>#onPackagesNamed:
>
> @Yuri, can you change that.
>
>
> And I think we should fix RBParser.
>
>
> 2015-09-16 11:30 GMT+02:00 Thierry Goubier <[hidden email]>:
> Nicolai,
>
> can you try with the RBParser directly? I believe Opal uses the RBParser.
>
> RBParser parseMethod: 'createRedMorph
> ^ (self new color:Color red); yourself'
>
> Oh, RBParser sees it as:
>
> self new
> color: Color red;
> yourself
>
> :)
>
> Thierry
>
>
> 2015-09-16 10:56 GMT+02:00 Nicolai Hess <[hidden email]>:
> The following method compiles with Opal:
>
> createRedMorph
> ^ (self new color:Color red); yourself
>
> but gives a syntax error with the old compilers parser
>
> createRedMorph
> ^ (self new color:Color red)End of block expected -> ; yourself
>
>
> removing the parenthesis of course works for both.
> Who is right ?
>
>
> (for those who understand the ParseTreeSearcher syntax, how would
> a search expression look, for finding code like:
>
> "(some expression);yourself"
>
>
> nicolai