[WIP] Updated json string literal based on elcritch's work

[tshort]

The aim of this PR is to update and simplify @elcritch's PR #113.

The single-quote option is removed. There's also no option to pass the dicttype. I tried using a trailing argument for this, but I couldn't find an eval option that worked.

It's marked as WIP because there's some extra junk in there for my failed tries to get dicttype to work. Someone else may have a suggestion. In any case, it needs to be cleaned up.

[tshort]

Any comments on this? Objections to merging?

The test failures are on Julia master and don't relate to this PR.

[elcritch]

I'll be able to take a look at it soon. Hopefully tomorrow. 

On Mon, Dec 14, 2015 at 6:13 PM -0800, "Tom Short" [email protected] wrote:

Any comments on this? Objections to merging?

The test failures are on Julia master and don't relate to this PR.

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[TotalVerb]

this function can probably be taken out, parse can be used directly

[TotalVerb]

As is, I'm not convinced this is useful—it doesn't save much typing over JSON.parse. It also boils down to macro json_str(x) JSON.parse(x) end which someone can trivially implement if needed (say, for avoiding runtime cost... though deferring the cost to compile time doesn't seem any better).

But one feature that would be nice would be interpolation:

const x = "World"
json"""
{
    "Hello": $x
}
"""

to produce Dict("Hello" => "World").

This interpolation feature is supported by Cxx.jl, MATLAB.jl, and a similar feature has been experimentally implemented in Scala.

[TotalVerb]

remove the test instead of commenting it out?

[elcritch]

@TotalVerb having string interpolation in the string macro would be very useful, IMHO. Unfortunately I couldn't find any documentation on how string interpolation is done by on normal Julia parse/compile. It appears you either get string interpolation or you can do string macros.

[StefanKarpinski]

String interpolation can't be done in full generality in a string macro since the parser needs to call itself recursively in order to know when the string literal ends. You can approximate it, however, by looking for $ and using the parse function to find an expression. This will not support interpolation of string literals.

[TotalVerb]

@StefanKarpinski While what you say is entirely correct, this macro is typically used multiline, so string interpolation with string literals (as long as they are not also multiline) should work as expected. I hope to create a prototype soon.

[TotalVerb]

As I mentioned here, this macro doesn't really provide anything beyond JSON.parse("..."). A different package would be a better place for a replacement for literal dict syntax.