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https://issues.apache.org/jira/browse/JEXL-390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Dmitri Blinov updated JEXL-390:
-------------------------------
Description:
In Jexl pragmas are treated as statements syntactically, but do not find their
way to AST tree and this leads to strange bugs like in the following example
{code}
@Test
public void testBadPragmas() throws Exception {
final JexlEngine jexl = new
JexlBuilder().cache(1024).debug(true).create();
final JexlScript script = jexl.createScript("if (true) #pragma one 42");
JexlContext jc = new MapContext();
final Object result = script.execute(jc);
debuggerCheck(jexl);
}
{code}
While this partucular bug can be trivially fixed, in fact the whole idea to
allow putting pragmas for example inside a loop or inside if-branch is a
strange language design (I'm not aware of examples in other languages) as it
gives false idea of the pragma being controlled by script execution logic.
If there's no reason or use case to keep this design as is, my proposal is to
make a grammar change and allow pragmas to be declared only at the top of the
script. Another point to change current pragma implementation is that pragmas
can not be used with expressions, e.g. no way to specify standard options /
imports.
was:
In Jexl pragmas are treated as statements syntactically, but do not find their
way to AST tree and this leads to strange bugs like in the following example
{code}
@Test
public void testBadPragmas() throws Exception {
final JexlEngine jexl = new
JexlBuilder().cache(1024).debug(true).create();
final JexlScript script = jexl.createScript("if (true) #pragma one 42");
JexlContext jc = new MapContext();
final Object result = script.execute(jc);
debuggerCheck(jexl);
}
{code}
While this partucular bug can be trivially fixed, in fact the whole idea to
allow putting pragmas inside a loop or inside if-branch is a strange language
design (I'm not aware of examples in other languages) as it gives false idea of
the pragma being controlled by script execution logic.
If there's no reason or use case to keep this design as is, my proposal is to
make a grammar change and allow pragmas to be declared only at the top of the
script
> Pragmas should not be statements
> --------------------------------
>
> Key: JEXL-390
> URL: https://issues.apache.org/jira/browse/JEXL-390
> Project: Commons JEXL
> Issue Type: Improvement
> Reporter: Dmitri Blinov
> Priority: Minor
>
> In Jexl pragmas are treated as statements syntactically, but do not find
> their way to AST tree and this leads to strange bugs like in the following
> example
> {code}
> @Test
> public void testBadPragmas() throws Exception {
> final JexlEngine jexl = new
> JexlBuilder().cache(1024).debug(true).create();
> final JexlScript script = jexl.createScript("if (true) #pragma one
> 42");
> JexlContext jc = new MapContext();
> final Object result = script.execute(jc);
> debuggerCheck(jexl);
> }
> {code}
> While this partucular bug can be trivially fixed, in fact the whole idea to
> allow putting pragmas for example inside a loop or inside if-branch is a
> strange language design (I'm not aware of examples in other languages) as it
> gives false idea of the pragma being controlled by script execution logic.
> If there's no reason or use case to keep this design as is, my proposal is to
> make a grammar change and allow pragmas to be declared only at the top of the
> script. Another point to change current pragma implementation is that pragmas
> can not be used with expressions, e.g. no way to specify standard options /
> imports.
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