groovy

Shorther syntax for catching multiple exceptions at once

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Description

John Wilson suggested this improved syntax for catching several exceptions at once:

This has been suggested for Java
http://members.capmac.org/~orb/blog.cgi/tech/java/Better_exception_sy.html

I would have thought it's trivial to do in Groovy

try { 
    Field field = someClass.getDeclaredField(someField); 
    someValue = field.getInt(Barcode.class); 
} catch (SecurityException, NoSuchFieldException e) { 
    // do something else with the exception 
}

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Guillaume Laforge added a comment -

See the thread on the mailing-list for further suggestions:
http://www.nabble.com/Multiple-exception-types-in-a-single-catch-block-tf4086071.html

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Guillaume Laforge added a comment - See the thread on the mailing-list for further suggestions: http://www.nabble.com/Multiple-exception-types-in-a-single-catch-block-tf4086071.html
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Aaron Digulla added a comment -

The catch statement doesn't look quite right. On one hand, there must be only a single "e", OTOH, we have two types. On the ML, there have been two suggestions:

} catch (SecurityException | NoSuchFieldException e) {

and

} catch (SecurityException, NoSuchFieldException) {
   // this is a closure; you can find the exception in "it"
}

Personally, I like the closure idea very much, especially when I can define the closure elsewhere! That would allow to override the default error handling which opens a whole new world of ways to deal with errors.

As for "|" vs. ",": The bar would express the "OR"-iness of the statement better but IMHO, it's just a list of types and lists use ",". Also, comma is easier to type.

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Aaron Digulla added a comment - The catch statement doesn't look quite right. On one hand, there must be only a single "e", OTOH, we have two types. On the ML, there have been two suggestions: } catch (SecurityException | NoSuchFieldException e) { and } catch (SecurityException, NoSuchFieldException) { // this is a closure; you can find the exception in "it" } Personally, I like the closure idea very much, especially when I can define the closure elsewhere! That would allow to override the default error handling which opens a whole new world of ways to deal with errors. As for "|" vs. ",": The bar would express the "OR"-iness of the statement better but IMHO, it's just a list of types and lists use ",". Also, comma is easier to type.
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Paul King added a comment -

See also:
http://www.javac.info/Multicatch.html

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Paul King added a comment - See also: http://www.javac.info/Multicatch.html
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Guillaume Laforge added a comment -

Setting the fix version to 1.8, to adapt to the multicatch proposal for JDK / Java 7

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Guillaume Laforge added a comment - Setting the fix version to 1.8, to adapt to the multicatch proposal for JDK / Java 7
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Cedric Champeau added a comment -

Here's a patch which adds support for Java 7 style multicatches :

try {
...
} catch (IOException | NullPointerException e) {
...
}

It translates this as a sequence of catch blocks with the same body.

All unit tests pass. Note that I had some troubles with the SourcePrinter, and I'm not sure I'm doing things correctly at that place. Feel free to review.

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Cedric Champeau added a comment - Here's a patch which adds support for Java 7 style multicatches : try { ... } catch (IOException | NullPointerException e) { ... } It translates this as a sequence of catch blocks with the same body. All unit tests pass. Note that I had some troubles with the SourcePrinter , and I'm not sure I'm doing things correctly at that place. Feel free to review.
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Guillaume Laforge added a comment -

For reference, the Project Coin JSR details about the multicatch exception can be found here:
http://jcp.org/aboutJava/communityprocess/edr/jsr334/index.html

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Guillaume Laforge added a comment - For reference, the Project Coin JSR details about the multicatch exception can be found here: http://jcp.org/aboutJava/communityprocess/edr/jsr334/index.html
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Cedric Champeau added a comment -

Reopening to provide a patch for the "final" modifier not being supported

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Cedric Champeau added a comment - Reopening to provide a patch for the "final" modifier not being supported
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Cedric Champeau added a comment -

The following patch fixes the "final" modifier issue by supporting the syntax, but without giving any semantics to it. See http://groovy.329449.n5.nabble.com/This-is-a-new-bug-td4258524.html

Adds tests cases too.

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Cedric Champeau added a comment - The following patch fixes the "final" modifier issue by supporting the syntax, but without giving any semantics to it. See http://groovy.329449.n5.nabble.com/This-is-a-new-bug-td4258524.html Adds tests cases too.

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  • Assignee:
    Cedric Champeau
    Reporter:
    Guillaume Laforge
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