[#CLJ-1023] non-tail-position try block breaks mutable fields in deftype - Clojure JIRA

Details

Type: Defect
Status: Closed
Priority: Minor
Resolution: Declined
Affects Version/s: Release 1.3, Release 1.4
Fix Version/s: None
Component/s: None
Labels:
None

Description

The :unsynchronized-mutable fields of a deftype cannot be set! inside a try block that is not in tail position of the method.

See file *demonstration.clj* for an complete code example.

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demonstration.clj

08/Jul/12 4:20 PM

0.9 kB

Stuart Sierra

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Rich Hickey made changes - 05/Sep/12 6:46 AM

Field	Original Value	New Value
Assignee		Rich Hickey [ richhickey ]

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Rich Hickey added a comment - 05/Sep/12 7:07 AM - edited

I looked at this. The problem is that non-tail try blocks turn into closures, and thus the field gets propagated as a constant. IOW this can't work:

(deftype Foo4 [^:unsynchronized-mutable x]
  MutableX
  (set-x [this v]
    ((fn [] (set! x v)))
    v))

I'm not going to re-evaluate the try/closure approach right now, so I recommend you make a helper method that just does the assignment and then call that in the bigger context, as a workaround.

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Rich Hickey added a comment - 05/Sep/12 7:07 AM - edited I looked at this. The problem is that non-tail try blocks turn into closures, and thus the field gets propagated as a constant. IOW this can't work:

(deftype Foo4 [^:unsynchronized-mutable x]
  MutableX
  (set-x [this v]
    ((fn [] (set! x v)))
    v))

I'm not going to re-evaluate the try/closure approach right now, so I recommend you make a helper method that just does the assignment and then call that in the bigger context, as a workaround.

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Timothy Baldridge added a comment - 03/Dec/12 10:55 AM

Closing this as it requires more than a simple bug fix. If you feel that Rich's work-around is unsatisfactory please create a clojure-dev discussion about rewriting try-catch.

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Timothy Baldridge added a comment - 03/Dec/12 10:55 AM Closing this as it requires more than a simple bug fix. If you feel that Rich's work-around is unsatisfactory please create a clojure-dev discussion about rewriting try-catch.

Timothy Baldridge made changes - 03/Dec/12 10:55 AM

Resolution		Declined [ 2 ]
Status	Open [ 1 ]	Closed [ 6 ]

People

Assignee:

Rich Hickey

Reporter:

Stuart Sierra

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Dates

Created:

08/Jul/12 4:20 PM

Updated:

03/Dec/12 10:55 AM

Resolved:

03/Dec/12 10:55 AM