[Pharo-project] [ENH] Syntax extension for continuations

Levente Uzonyi leves at elte.hu
Mon Nov 1 04:24:13 CET 2010


On Mon, 1 Nov 2010, Igor Stasenko wrote:

> Here is more examples (found by searching .sources file with 3 or more '(((' ).
>
> ContextPart>>handleSignal:
>
> (((self tempAt: 1) handles: exception) and: [self tempAt: 3]) ifFalse: [
> 	^ self nextHandlerContext handleSignal: exception].
>
>
> self tempAt: 1 ;; handles: exception ;; and: [self tempAt: 3] ;; ifFalse: [
> 		^ self nextHandlerContext handleSignal: exception].


What about this?

((self tempAt: 3) and: [ (self tempAt: 1) handles: exception ]) ifFalse: [
 	^ self nextHandlerContext handleSignal: exception].

>
>
> Bezier3Segment.
>
> before:
>
> bezier2SegmentCount: pixelError
> 	"Compute the number of quadratic bezier segments needed to approximate
> 	this cubic with no more than a specified error"
> 	| a |
> 	a := (start x negated @ start y negated) + (3 * via1) - (3 * via2) +
> (end).
> 	^ (((a r / (20.0 * pixelError)) raisedTo: 0.333333) ceiling) max: 1.
>
> after:
>
> bezier2SegmentCount: pixelError
> 	"Compute the number of quadratic bezier segments needed to approximate
> 	this cubic with no more than a specified error"
> 	| a |
> 	a := start x negated @ start y negated ;; + (3 * via1) - (3 * via2) +
> end.
> 	^ a r / (20.0 * pixelError) raisedTo: 0.333333 ;; ceiling max: 1.

There are 2 superfluous parenthesis in the original code (which you 
omitted in your code). Here's the same without them:

 	^(a r / (20.0 * pixelError) raisedTo: 0.333333) ceiling max: 1.

If I want to be "tricky", I can even remove another parenthesis:

 	^(0.05 * a r / pixelError raisedTo: 0.333333) ceiling max: 1.

>
>
> ZipArchive
>
> before:
>
> lastIndexOfPKSignature: aSignature in: data
> 	"Answer the last index in data where aSignature (4 bytes long)
> occurs, or 0 if not found"
> 	| a b c d |
> 	a := aSignature first.
> 	b := aSignature second.
> 	c := aSignature third.
> 	d := aSignature fourth.
> 	(data size - 3) to: 1 by: -1 do: [ :i |
> 		(((data at: i) = a)
> 			and: [ ((data at: i + 1) = b)
> 				and: [ ((data at: i + 2) = c)
> 					and: [ ((data at: i + 3) = d) ]]])
> 						ifTrue: [ ^i ]
> 	].
> 	^0
>
> after:
>
> lastIndexOfPKSignature: aSignature in: data
> 	"Answer the last index in data where aSignature (4 bytes long)
> occurs, or 0 if not found"
> 	| a b c d |
> 	a := aSignature first.
> 	b := aSignature second.
> 	c := aSignature third.
> 	d := aSignature fourth.
> 	data size - 3 to: 1 by: -1 do: [ :i |
> 		data at: i ;; = a
> 			and: [ data at: i + 1 ;; = b
> 				and: [ data at: i + 2 ;; = c
> 					and: [ data at: i + 3 ;; = d ]]]
> 						ifTrue: [ ^i ]
> 	].
> 	^0

Same as above, superfluous parenthesis. This is what you get after 
removing 5 of them and a bit of reformatting:

 	data size - 3 to: 1 by: -1 do: [ :i |
 		(data at: i) = a and: [
 			(data at: i + 1) = b and: [
 			(data at: i + 2) = c and: [
 			(data at: i + 3) = d ] ] ])
 				ifTrue: [ ^i ]
 	].



>
>
> Character
>
> before:
>
> asUppercase
> 	"If the receiver is lowercase, answer its matching uppercase Character."
> 	"A tentative implementation.  Eventually this should consult the
> Unicode table."
>
> 	| v |
> 	v := self charCode.
> 	(((8r141 <= v and: [v <= 8r172]) or: [16rE0 <= v and: [v <= 16rF6]])
> or: [16rF8 <= v and: [v <= 16rFE]])
> 		ifTrue: [^ Character value: value - 8r40]
> 		ifFalse: [^ self]
>
> after:
>
> asUppercase
> 	"If the receiver is lowercase, answer its matching uppercase Character."
> 	"A tentative implementation.  Eventually this should consult the
> Unicode table."
>
> 	| v |
> 	v := self charCode.
> 	8r141 <= v and: [v <= 8r172] ;; or: [16rE0 <= v and: [v <= 16rF6]] ;;
> or: [16rF8 <= v and: [v <= 16rFE]] ;;
> 		ifTrue: [^ Character value: value - 8r40]
> 		ifFalse: [^ self]

There's #between:and: or you can use better formatting to improve 
readability here:

 	((v between: 8r141 and: 8r172) or: [
 		v between: 16rE0 and: 16rF6 ] or: [
 		v between: 16rF8 and: 16rFE ])
 			ifTrue: [ ^Character value: value - 8r40].

or

 	((8r141 <= v and: [ v <= 8r172 ]) or: [
                 (16rE0 <= v and: [ v <= 16rF6 ]) or: [
                 16rF8 <= v and: [ v <= 16rFE ] ] ])
 			ifTrue: [ ^Character value: value - 8r40].


Levente

>
>
>
> -- 
> Best regards,
> Igor Stasenko AKA sig.
>
>




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