Is it possible to merge multiple module definitions in a single file and avoid possible clashes with Rails autoloading ?
Thanks !
I am not sure I understood how this would help “to avoid possible clashes with Rails autoloading”, but the answer is “yes”: one might define as many modules, classes, constants and whatever is defineable in the single file.
Ruby has no restriction on the relation between file names and modules/classes names. One might define modules A1 and A2 in file b.rb. Standard lib/namespace/class_name.rb convetion is the convention only, as soon as file is required, it’s content is being loaded.
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My Grails (2.4.2) app was created with a bunch of "default/standard" resource bundles:
myapp/
grails-app/
i18n/
messages.properties
messages_fr.properties
I would now like to create my own "custom" resource bundle, that is, define properties in a file outside of these standard messages*.properties files that myapp was created with.
According to the i18n documentation, all bundles need to be prefixed with messages and suffixed .properties. So I added two new props files, one for English and one for French:
myapp/
grails-app/
i18n/
messages.properties
messages_fr.properties
messages_myapp.properties
messages_myapp_fr.properties
For one, I'm not 100% sure I'm interpreting the docs correctly. So if anything about my 2 new props files jumps out at you as being incorrect, please start by letting me know!
Having said that, in all the example from those docs, I don't see where you specify the bundle to use. All of the examples look like this:
<g:message code="fizz.buzz.foo" />
But what if I have a fizz.buzz.foo property defined in both messages_blah.properties and messages_bar.properties?
So I ask: How do I add my own custom resource bundles, and how do I properly refer to them from inside a GSP?
To answer your question you have to understand what Grails (well, Spring really) is doing to accomplish this.
You are on the right path with the multiple files. What you have outlined there matches the documentation and will work.
However, under the covers what is really being done is they are being combined into a single bundle (per language). So there is no need to tell Grails/Spring which bundle to use.
Finally, what happens when the same key is defined multiple times? The first one matched wins. I seem to recall that the order in which the bundles are combined is in file name order, though you should be able to test this pretty quickly.
Hope this helps, and best of luck!
I'm writing an iOS app, "Best Korea". My organization name is "Srsly.co". I'm going to write re-usable "News" libraries that I'll use across my apps.
Each iOS app will have its own app-wide constants in a .h file, and the library code will have its constants as well in header files. I'll also have tests for each of these projects.
Is this the standard way of doing things?
In Ruby, Python, Java, etc., I'd set up namespaces along these lines:
co.srsly.bestkorea
co.srsly.bestkorea.test
co.srsly.newslib
co.srsly.newslib.test
As far as I can see, the Objective-C pattern is for each developer to choose two or three upper-case letters and prefix every class name with them.
So in my case, I'm thinking I'd choose BK as the app's classname prefix and NL for the news lib code? Am I thinking about this the right way?
EDIT: I'm considering not using namespacing at all in my application code as discussed here.
You're correct that Objective-C doesn't have built in support for namespaces, and the common solution is to use uppercase prefixes on each class. Note that Apple has stated that two letter prefixes are reserved for their use, so you should use three letter prefixes for your own classes. Otherwise, your suggested approach is the normal thing to do.
There is no NameSpace in Objective-C as you are expecting in Java.
Objective-C uses class Prefix like NS, UI, CG, CF etc to safely remove name space collision.
And it would be better to use 3 letter Prefix for your class.
You should read this : What is the best way to solve an Objective-C namespace collision?
I have a mnesia table callable from two modules- obviously both modules needing to refer to the records of the table.
Is there any way to declare the record type in one module and use it in the other module, without having to redefine and maintain the declaration in two modules? At the moment I had to declare the record type in each module.
You can declare it in an include file (in the typical app, it would be found in an include directory from the root of the app), then include it in each module.
-include("myrecords.hrl").
To see a practical example, I'll refer you to the rebar repo so you can see how this is typically structured: https://github.com/rebar/rebar
I'm currently writing some functions that are related to lists that I could possibly be reused.
My question is:
Are there any conventions or best practices for organizing such functions?
To frame this question, I would ideally like to "extend" the existing lists module such that I'm calling my new function the following way: lists:my_funcion(). At the moment I have lists_extensions:my_function(). Is there anyway to do this?
I read about erlang packages and that they are essentially namespaces in Erlang. Is it possible to define a new namespace for Lists with new Lists functions?
Note that I'm not looking to fork and change the standard lists module, but to find a way to define new functions in a new module also called Lists, but avoid the consequent naming collisions by using some kind namespacing scheme.
Any advice or references would be appreciated.
Cheers.
To frame this question, I would ideally like to "extend" the existing lists module such that I'm calling my new function the following way: lists:my_funcion(). At the moment I have lists_extensions:my_function(). Is there anyway to do this?
No, so far as I know.
I read about erlang packages and that they are essentially namespaces in Erlang. Is it possible to define a new namespace for Lists with new Lists functions?
They are experimental and not generally used. You could have a module called lists in a different namespace, but you would have trouble calling functions from the standard module in this namespace.
I give you reasons why not to use lists:your_function() and instead use lists_extension:your_function():
Generally, the Erlang/OTP Design Guidelines state that each "Application" -- libraries are also an application -- contains modules. Now you can ask the system what application did introduce a specific module? This system would break when modules are fragmented.
However, I do understand why you would want a lists:your_function/N:
It's easier to use for the author of your_function, because he needs the your_function(...) a lot when working with []. When another Erlang programmer -- who knows the stdlb -- reads this code, he will not know what it does. This is confusing.
It looks more concise than lists_extension:your_function/N. That's a matter of taste.
I think this method would work on any distro:
You can make an application that automatically rewrites the core erlang modules of whichever distribution is running. Append your custom functions to the core modules and recompile them before compiling and running your own application that calls the custom functions. This doesn't require a custom distribution. Just some careful planning and use of the file tools and BIFs for compiling and loading.
* You want to make sure you don't append your functions every time. Once you rewrite the file, it will be permanent unless the user replaces the file later. Could use a check with module_info to confirm of your custom functions exist to decide if you need to run the extension writer.
Pseudo Example:
lists_funs() -> ["myFun() -> <<"things to do">>."].
extend_lists() ->
{ok, Io} = file:open(?LISTS_MODULE_PATH, [append]),
lists:foreach(fun(Fun) -> io:format(Io,"~s~n",[Fun]) end, lists_funs()),
file:close(Io),
c(?LISTS_MODULE_PATH).
* You may want to keep copies of the original modules to restore if the compiler fails that way you don't have to do anything heavy if you make a mistake in your list of functions and also use as source anytime you want to rewrite the module to extend it with more functions.
* You could use a list_extension module to keep all of the logic for your functions and just pass the functions to list in this function using funName(Args) -> lists_extension:funName(Args).
* You could also make an override system that searches for existing functions and rewrites them in a similar way but it is more complicated.
I'm sure there are plenty of ways to improve and optimize this method. I use something similar to update some of my own modules at runtime, so I don't see any reason it wouldn't work on core modules also.
i guess what you want to do is to have some of your functions accessible from the lists module. It is good that you would want to convert commonly used code into a library.
one way to do this is to test your functions well, and if their are fine, you copy the functions, paste them in the lists.erl module (WARNING: Ensure you do not overwrite existing functions, just paste at the end of the file). this file can be found in the path $ERLANG_INSTALLATION_FOLDER/lib/stdlib-{$VERSION}/src/lists.erl. Make sure that you add your functions among those exported in the lists module (in the -export([your_function/1,.....])), to make them accessible from other modules. Save the file.
Once you have done this, we need to recompile the lists module. You could use an EmakeFile. The contents of this file would be as follows:
{"src/*", [verbose,report,strict_record_tests,warn_obsolete_guard,{outdir, "ebin"}]}.
Copy that text into a file called EmakeFile. Put this file in the path: $ERLANG_INSTALLATION_FOLDER/lib/stdlib-{$VERSION}/EmakeFile.
Once this is done, go and open an erlang shell and let its pwd(), the current working directory be the path in which the EmakeFile is, i.e. $ERLANG_INSTALLATION_FOLDER/lib/stdlib-{$VERSION}/.
Call the function: make:all() in the shell and you will see that the module lists is recompiled. Close the shell.
Once you open a new erlang shell, and assuming you exported you functions in the lists module, they will be running the way you want, right in the lists module.
Erlang being open source allows us to add functionality, recompile and reload the libraries. This should do what you want, success.
If i want to move /lib/foo_bar.rb to /lib/tidy/foo_bar.rb or even /lib/tidy/somestuff/foo_bar.rb
must i declare FooBar to be module Tidy or module Tidy::Somestuff
in other words must the modules match the directory structure?
Yes, if you don't want to specify the load path. You can add lib/tidy to the LOAD_PATH and then Rails will find it, but it's easier to just stick with the conventions