using modules in modules?

Regarding modules, the upload for every piece of code happens in two steps:

1. parse the code (or module) to upload for every instance of require("noduleName");. for each found module do 1.

2. upload - code or module - for which the (nested) required modules have just been loaded.

Note: you can 'escape' step one by using a variable... But in order that the code has what it needs to run successfully, the module has to be uploaded separately.

var moduleName = "myModule";
require(moduleName);

Above code will fail with already on upload because it is all in top-level/level 0 and interpreted when arriving at Espruino with this message:

 1v86 Copyright 2016 G.Williams
>echo(0);
ERROR: SD card must be setup with E.connectSDCard first
WARNING: Module "myModule" not found
=undefined
>

You notice two things:

1. 2. ```WARNING: Module "myModule" not found```
   
   Bottom line the 2nd item is what matters. Interestingly though is that ***when you have an SD memory card connected and mounted*** and "myModule.js" or "myModule.min.js" (minified version of "myModule.js") on it, the module is found on the SD memory card, loaded and stored *evaluated* in the cache.
   
   You can actually ask Espruino which modules are cached. Enter in the console [Modules.getCached()](http://www.espruino.com/Reference#l_Modules_getCached) (command, reference):
   
   

Modules.getCached();

What you would expect is (according to [reference documentation](http://www.espruino.com/Reference#l_Modules_getCached)):

=[
]

***but*** you get:

=[
"myModule"
]

You will get what you expected with 'empty' Espruino (after you enter command ```reset()```. But for what ever reason, @Gordon decided to make the (map) entry anyway on require() but put the value undefined... and unfortunately there is *NO* (easy and) quiet (programmatic) way to figure out if the module is actually there, successfully loaded... *NOT even with a a try catch block* (Upload below code - copy-pasted into editor - and enter command ```onInit()```:

var moduleName = "myModule";
var myModule = "The module was not found";
function onInit() {
try {

  myModule = require(moduleName);

} catch(x) {

  console.log("Programmatically caught exception: " + x);

}
var namesOfCachedModules = Modules.getCached();
console.log("Cached modules:");
console.log(namesOfCachedModules);
if (typeof myModule === "string") {

console.log("myModule = " + myModule);

} else {

console.log("myModule was set to " + myModule);

}
}

@Gordon, ***can that be fixed? ...backward compatible?*** Not successfully loaded modules should not show in the list or there should be an easy way to get to that info about the module - without Espruino throwing a fit / writing to console (and may be mess up if console not connected...) - or, worst case, with cumbersome try-catch-block that actually works... Try-catch is obviously not working as can be seen by the output produced (or not produces as expected by the catch-block), but sets the variable ```myModule```.

1v86 Copyright 2016 G.Williams
echo(0);
=undefined
onInit()
ERROR: SD card must be setup with E.connectSDCard first
WARNING: Module "myModule" not found
Cached modules:
[
"myModule"
]
=undefined

(Since ```Modules``` is natively implemented, there is no access to the 'map' that could just return ```null``` for not uploaded modules and ```not-null/module object``` for successfully uploaded modules.)

Back to hat I wanted to continue with (Sorry for this (even me) surprising detour...): Enter following commands and you get empty list of cached modules.

reset();

Modules.getCached();

Now we 'hand'-fix the issue by entering the issue by entering the following in the console (copy-paste):

Modules.addCached(

"myModule"

, "exports = \"a simple String value: 'Hi!'\";");

Then we enter in console (copy-paste):

Modules.getCached();
var myModule = require("myModule");
console.log("myModules is: " + myModule);

And the expected output is:

Modules.getCached();
=[
"myModule"
]
="a simple String value: 'Hi!'"
console.log("myModules is: " + myModule);
myModules is: a simple String value: 'Hi!'
=undefined

We could not directly upload and execute previous code, because first thing of upload is ```reset()``` which just wipes out our 'hand'-fix. But we can add the 'hand'-fix to the code as first thing and then proceed as before.

Modules.addCached(

"myModule"

, "exports = \"a simple String value: 'Hi!'\";");
var moduleName = "myModule";
var myModule = "The module was not found";
function onInit() {
try {

  myModule = require(moduleName);

} catch(x) {

  console.log("Programmatically caught exception: " + x);

}
var namesOfCachedModules = Modules.getCached();
console.log("Cached modules:");
console.log(namesOfCachedModules);
if (typeof myModule === "string") {

console.log("myModule = " + myModule);

} else {

console.log("myModule was set to " + myModule);

}
}

And here the expected output from output and entering ```onInit()``` command:

1v86 Copyright 2016 G.Williams
echo(0);
=undefined
onInit();
Cached modules:
[
"myModule"
]
myModule = a simple String value: 'Hi!'
=undefined

```

I guess this should put to peace many of the questions in regard of modules.

...another 2 cents from my part.

PS: Read through related Struggling with modules conversation.