[
https://issues.apache.org/jira/browse/FREEMARKER-169?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Dániel Dékány closed FREEMARKER-169.
------------------------------------
> Various inconsistencies around c builtin
> ----------------------------------------
>
> Key: FREEMARKER-169
> URL: https://issues.apache.org/jira/browse/FREEMARKER-169
> Project: Apache Freemarker
> Issue Type: Bug
> Affects Versions: 2.3.29
> Environment: OS: Ubuntu 20.04.1 LTS (virtual machine)
> Hardware: 32GB; 6 core processor (virtual machine)
> Java Version: 1.8.0_172
> Reporter: Andrew Cook
> Priority: Minor
> Fix For: 2.3.31
>
>
> While trying to build a custom template number formatter, I've encountered
> various inconsistencies around the C builtin, C NumberFormat, and related
> documentation.
> Description follows.
> h2. c built-in Behavior
> My use case requires XML compatible NaN/INF representations, and rather than
> write the string format representation logic myself, I wanted to leverage the
> logic used for the c built-in, since the [c-builtin
> documentation|https://freemarker.apache.org/docs/ref_builtins_number.html#ref_builtin_c]
> states that "[i]f the {{incompatible_improvements}} FreeMarker configuration
> setting is set to 2.3.24 or higher (also if it's set to 2.3.20 or higher and
> you are outside a string literal), this built-in will return {{"INF"}},
> {{"-INF"}} and {{"NaN"}} for positive/negative infinity and IEEE floating
> point Not-a-Number, respectively."
> In my project, we have {{incompatible_improvements}} version set to 2.3.29:
> {code:java}
> cfg = new Configuration(Configuration.VERSION_2_3_29);
> {code}
> So the expected behavior for the c-builtin is that INF, -INF, and NaN are
> represented as such, and it does, with val=Double.POSITIVE_INFINITY in the
> root context:
> {code:java}
> <MyDocument>
> <myField>${val?c}</myField>
> </MyDocument>{code}
> Yields:
> {code:java}
> <MyDocument>
> <myField>INF</myField>
> </MyDocument>{code}
> Great, just what I want.
> h2. CNumberFormat Behavior Mismatch
> To access this behavior for my custom template number format, I tried to use
> [Environment::getCNumberFormat|https://github.com/apache/freemarker/blob/v2.3.29/src/main/java/freemarker/core/Environment.java#L1473]
> since it's documentation says that it "[r]eturns the NumberFormat used for
> the c built-in." Again, that should be great, since the c built-in has
> exactly the behavior I want.
> Went I implemented this and made a test, however, this code:
>
> {code:java}
> environment.getCNumberFormat().format(Double.POSITIVE_INFINITY);
> {code}
> Returned "∞". Not if you look at [the
> code|https://github.com/apache/freemarker/blob/v2.3.29/src/main/java/freemarker/core/Environment.java#L1477]
> because under the hood, this ended up returning [a DecimalFormat
> object|https://github.com/apache/freemarker/blob/v2.3.29/src/main/java/freemarker/core/Environment.java#L104],
> contra was is suggested by the various documentation, including, for the c
> built-in: "[e]arlier it has returned what {{java.text.DecimalFormat}} did
> with US locale, none of which is understood by any (common) computer
> language." It seems like it actually still just returns DecimalFormat in some
> cases.
>
> h2. string.computer Behavior Mismatch
> Further inconsistency comes in with the string.computer builtin. The [string
> builtin for numbers
> documentation|https://freemarker.apache.org/docs/ref_builtins_number.html#ref_builtin_string_for_number]
> states that "[t]here are four predefined number formats: {{computer}},
> {{currency}}, {{number}}, and {{percent}}. The exact meaning of these is
> locale (nationality) specific, and is controlled by the Java platform
> installation, not by FreeMarker, except for {{computer}}, which uses the same
> formatting as [the {{c}}
> built-in|https://freemarker.apache.org/docs/ref_builtins_number.html#ref_builtin_c].";
> So the expected behavior of the following should be the same as my use of the
> c built-in above:
>
> {code:java}
> <MyDocument>
> <myField>${val?string.computer}</myField>
> </MyDocument>
> {code}
> But it's not:
>
>
> {code:java}
> <MyDocument>
> <myField>∞</myField>
> </MyDocument>
> {code}
> The cause for this is the same as the cause of the other inconsistency, since
> it seems that the computer number format for the string builtin for numbers
> [just uses
> Environment::getCNumberFormat|https://github.com/apache/freemarker/blob/v2.3.29/src/main/java/freemarker/core/JavaTemplateNumberFormatFactory.java#L58],
> which as I've already mentioned has the same problem.
> h2. Conclusion
> Either documentation in multiple places is wrong and should be updated or the
> implementation for all this is wrong because the formatting logic isn't
> shared (as, indeed, it isn't, since [the c built-in works totally
> differently|https://github.com/apache/freemarker/blob/v2.3.29/src/main/java/freemarker/core/BuiltInsForMultipleTypes.java#L94]).
> Please either update the documentation or the implementation to resolve these
> inconsistencies. It was quite confusing for me and took a good bit of digging
> to figure out what was going on.
> Let me know if you need any other information
>
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
