How do I save a dynamically generated Lisp system in external files? - common-lisp

Basically, I want to be able to generate class definitions, compile the system, and save it for reuse. Would that involve a code walker, or is there a simpler option?
(save-lisp-and-die "isn't going to work for me")
Expanding to explain. I'm generating systems based on OpenAPI definitions, so a system roughly corresponds to an API client.
There will be dozens, if not hundreds of these.
The idea is to NOT keep them all in the image, but load at run time as required.

I see two possible routes here, and to some extent, I suspect they mainly differ in "the last mile" (as it were).
The route you seem to have settled on, run-time definition of classes and functions.
A route whereby you generate your function/class forms, but don't go the full way to get them "Live" in the image and instead emit the form(s) to a file.
I suspect that it would be possible to have most of the generating code shared between the two and for the first route have a wrapping macro that effectively returns a PROGN, and in the second calls a function to pretty-print what the macro would have returned on a stream.
Saying that, building a tailored environment and saving it to a "core" file is a pretty good way of getting excellent startup times.

Related

How do you use guards(1) with quilt(1)

One of the ancillary tools bundled with quilt is guards, which processes a list of guards and a configuration file matching guards and files, and outputs a list of files whose guard specifications match the provided guards.
However I can't figure how they're supposed to fit together: quilt(1) doesn't show any way to invoke a command to generate series files, I didn't find examples in the mans or the working copy, and the internets are less than helpful (all the hits talk about bedding).
I feel like guard has to be manually invoked whenever its "dependencies" change and the series file overwritten, is that the case? If so, how is data fed back the other way around e.g. when adding a new patch to the series, does it have to be manually synchronised to the guard file?
Background: a few years back I used mq quite a bit, but it integrates guards natively so the synchronisation back and forth is not an issue at all.

Benefits of using pyuic vs uic.loadUi

I am currently working with python and Qt which is kind of new for me coming from the C++ version and I realised that in the oficial documentation it says that an UI file can be loaded both from .ui or creating a python class and transforming the file into .py file.
I get the benefits of using .ui it is dynamically loaded so no need to transform it into python file with every change but what are the benefits of doing that?, Do you get any improvements in run time? Is it something else?
Thanks
Well, this question is dangerously near to the "Opinion-based" flag, but it's also a common one and I believe it deserves at least a partial answer.
Conceptually, both using the pyuic approach and the uic.loadUi() method are the same and behave in very similar ways, but with some slight differencies.
To better explain all this, I'll use the documentation about using Designer as a reference.
pyuic approach, or the "python object" method
This is probably the most popular method, especially amongst beginners. What it does is to create a python object that is used to create the ui and, if used following the "single inheritance" approach, it also behaves as an "interface" to the ui itself, since the ui object its instance creates has all widgets available as its attributes: if you create a push button, it will be available as ui.pushButton, the first label will be ui.label and so on.
In the first example of the documentation linked above, that ui object is stand-alone; that's a very basic example (I believe it was given just to demonstrate its usage, since it wouldn't provide a lot of interaction besides the connections created within Designer) and is not very useful, but it's very similar to the single inheritance method: the button would be self.ui.pushButton, etc.
IF the "multiple inheritance" method is used, the ui object will coincide with the widget subclass. In that case, the button will be self.pushButton, the label self.label, etc.
This is very important from the python point of view, because it means that those attribute names will overwrite any other instance attribute that will use the same name: if you have a function named "saveFile" and you name the button "saveFile", you won't have any [direct] access to that instance method any more as soon as setupUi is returned. In this case, using the single inheritance method might be helpful - but, in reality, you could just be more careful about function and object names.
Finally, if you don't know what the pyuic generated file does and what's it for, you might be inclined to use it to create your program. That is wrong for a lot of reasons, but, most importantly, because you might certainly realize at some point that you have to edit your ui, and merging the new changes with your modified code is clearly a PITA you don't want to face.
I recently answered a related question, trying to explain what happens when setupUi() is called in much more depth.
Using uic.loadUi
I'd say that this is a more "modular" approach, mostly because it's much more direct: as already pointed out in the question, you don't have to constantly regenerate the ui files each time they're modified.
But, there's a catch.
First of all: obviously the loading, parsing and building of an UI from an XML file is not as fast as creating the ui directly from code (which is exactly what the pyuic file does within setupUi()).
Then, there is at least one relatively small bug about layout contents margins: when using loadUi, the default system/form margins might be completely ignored and set to 0 if not explicitly set. There is a workaround about that, explained in Size of verticalLayout is different in Qt Designer and PyQt program (thanks to eyllanesc).
A comparison
pyuic approach
Pros:
it's faster; in a very simple test with a hundred buttons and a tablewidget with more than 1200 items I measured the following bests:
pyuic loading: 33.2ms
loadUi loading: 51.8ms
this ratio is obviously not linear for a multitude of reasons, but you can get the idea
if used with the single inheritance method, it can prevent accidental instance attribute overwritings, and it also means a more "contained" object structure
using python imports ensures a more coherent project structure, especially in the deployment process (having non-python files is a common source of problems)
the contents of those files are actually instructive, especially for beginners
Cons:
you always must remember to regenerate the python files everytime you update an ui; we all know how easy is to forget an apparently meaningless step like this might be, expecially after hours of coding: I've seen plenty of situations for which people was banging heads on desks (hopefully both theirs) for hours because of untraceable issues, before realizing that they just forgot to run pyuic or didn't run it on the right files; my own forehead still hurts ;-)
file tracking: you have to count two files for each ui, and you might forget one of them along the way when migrating/forking/etc, and if you forgot an ui file it possibly means that you have to recreate it completely from scratch
n00b alert: beginners are commonly led to think that the generated python file is the one to be used to create their programs, which is obviously wrong; unfortunately, the # WARNING! message is not clear enough (I've been almost begging the head PyQt developer about this); while this is obviously not an actual problem of this approach, right now it results in being so
some of the contents of a pyuic generated files are usually unnecessary (most importantly, the object name, which is used only for specific cases), and that's pretty obvious, since it's automatically generated ("you might need that, so better safe than sorry"); also, related to the issue above, people might be led to think that everything pyuic creates is actually needed for a GUI, resulting in unnecessary code that decreases its readability
loadUi method
Pros:
it's direct and immediate: you edit your ui on Designer, you save it (or, at least, you remember to do it...), and when you run your code it's already there; no fuss, no muss, and desks/foreheads are safe(r)
file tracking and deployment: it's just one file per ui, you can put all those ui files in a separate folder, you don't have to do anything else and you don't risk to forget something on the way
direct access to widgets (but this can be achieved using the multiple inheritance approach also)
Cons:
the layout issue mentioned above
possible instance attribute overwriting and no "ui" object "containment"
slightly slower loading
path and deployment: loading is done using os relative paths and system separators, so if you put the ui in a directory different from the py file that loads that .ui you'll have to consider that; also, some package managers use to compress everything, resulting in access errors unless paths are correctly managed
In my opinion, all considering, the loadUi method is usually the better choice. It doesn't distract me, it allows better conceptual compartmentation (which is usually good and also follows a pattern similar to MVC much more closely, conceptually speaking) and I strongly believe it as being far less prone to programmer errors, for a multitude of reasons.
But that's clearly a matter of choice.
We should also and always remember that, like every other choice we do, using ui files is an option.
There is people who completely avoids them (as there is people who uses them literally for anything), but, like everything, it all and always depends on the context.
A big benefit of using pyuic is that code autocompletion will work.
This can make programming much easier and faster.
Then there's the fact that everything loads faster.
pyuic6-Tool can be used to automate the call of pyuic6 when the application is run and only convert .ui files when they change.
It's a little bit longer to set up than just using uic.loadUi but the autocompletion is well worth it if you use something like PyCharm.

Generating files to multiple paths with Swagger Codegen?

I'm creating a template for our server-side codegen implementation, but I ran into an issue for a feature request...
The developers who are going to use the generated base want the following pattern (the generator is based on the dotnetcore):
Controllers
v{apiVersion}
{endpoint}ApiController : Controller, I{endpoint}Api
Interfaces
v{apiVersion}
I{endpoint}Api
I{endpoint}DataProvider
DataProviders
-v{apiVersion}
-{endpoint}DataProvider : I{endpoint}DataProvider
Both interfaces are the same, describing the endpoints. The DataProvider implementation will allow us to use DI to hot-swap the actual data provider/business logic layer during runtime.
The generated ApiControllers will refer to the IDataProviders, and use the actual implementation (the currently active one, that is). For that we're going to use dotnetcore's built-in dependency injection system.
However I can't seem to find a way to have the operations generator output to three different folders, based on the template. It will all end up jumbled in a single folder, and I will need to manually move them.
Is there a way to solve these requirements, or should I solve it all the time manually?

Use Julia to perform computations on a webpage

I was wondering if it is possible to use Julia to perform computations on a webpage in an automated way.
For example suppose we have a 3x3 html form in which we input some numbers. These form a square matrix A, and we can find its eigenvalues in Julia pretty straightforward. I would like to use Julia to make the computation and then return the results.
In my understanding (which is limited in this direction) I guess the process should be something like:
collect the data entered in the form
send the data to a machine which has Julia installed
run the Julia code with the given data and store the result
send the result back to the webpage and show it.
Do you think something like this is possible? (I've seen some stuff using HttpServer which allows computation with the browser, but I'm not sure this is the right thing to use) If yes, which are the things which I need to look into? Do you have any examples of such implementations of web calculations?
If you are using or can use Node.js, you can use node-julia. It has some limitations, but should work fine for this.
Coincidentally, I was already mostly done with putting together an example that does this. A rough mockup is available here, which uses express to serve the pages and plotly to display results (among other node modules).
Another option would be to write the server itself in Julia using Mux.jl and skip server-side javascript entirely.
Yes, it can be done with HttpServer.jl
It's pretty simple - you make a small script that starts your HttpServer, which now listens to the designated port. Part of configuring the web server is that you define some handlers (functions) that are invoked when certain events take place in your app's life cycle (new request, error, etc).
Here's a very simple official example:
https://github.com/JuliaWeb/HttpServer.jl/blob/master/examples/fibonacci.jl
However, things can get complex fast:
you already need to perform 2 actions:
a. render your HTML page where you take the user input (by default)
b. render the response page as a consequence of receiving a POST request
you'll need to extract the data payload coming through the form. Data sent via GET is easy to reach, data sent via POST not so much.
if you expose this to users you need to setup some failsafe measures to respawn your server script - otherwise it might just crash and exit.
if you open your script to the world you must make sure that it's not vulnerable to attacks - you don't want to empower a hacker to execute random Julia code on your server or access your DB.
So for basic usage on a small case, yes, HttpServer.jl should be enough.
If however you expect a bigger project, you can give Genie a try (https://github.com/essenciary/Genie.jl). It's still work in progress but it handles most of the low level work allowing developers to focus on the specific app logic, rather than on the transport layer (Genie's author here, btw).
If you get stuck there's GitHub issues and a Gitter channel.
Try Escher.jl.
This enables you to build up the web page in Julia.

How to handle changes in objects' structure in automated testing?

I’m curious to know how feasible it is to get away from the dependency onto the application’s internal structure when you create an automated test case. Or you may need to rewrite the test case when a developer modifies a part of the code for a bug fix, etc.
We could write several automated test cases based on the applications internal object structure, but lets assume that the object hierarchy changes after 6 months or so, how do we approach these kind of issues?
I can't speak for other testing tools but at least in QTP's case the testing tool introduces a level of abstraction over the application so that non-functional changes in the application often (but not always) have no effect on the way the testing tool identifies the object.
For example in QTP all web elements are considered to be direct children of the document so that changes in the DOM (such as additional tables) don't change the object's description.
In TestComplete, there are a couple of ways to make sure that the changed app structure does not break you tests.
You can set up the Aliases tree of the Name Mapping feature. In this case, if the app structure is changed, you need to modify the Aliases tree appropriately and your test will stay working without requirement to modify them.
You can use the Extended Find feature of the Name Mapping in order to ignore parts of the the actual object tree and search for a needed objects on deeper levels.
This is what I was forced to do after losing all my work twice due to changes on the DOM structure:
Every single time I need to work with an object, I use the Find function with the ID of the object, searching for the object on the Page object. This way, whenever the DOM gets updated, my tests still run smoothly.
The only thing that will break my tests is if the object's ID get changed, but that's not very probable to happen.
Here you can find some examples of the helper functions I use.

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