I'm implementing an internal DSL using ruby. I provide a command line tool to execute DSL scripts written in files (much like puppet). At first I was going to use load() to run the scripts, thing is, I want to be able to pass some context before I execute the script. I was hoping I could read a script in text form and treat it as a block and then have that block executed with some given context. Is something like this possible?
Or how are such things generally achieved? It can be done for sure because puppet does it. But before I can dig through its code base, I'm trying here.
Also, are there any nice small examples of internal DSL implementations I could look at?
Check following links please, a series of DSL articles.
http://www.ibm.com/developerworks/java/library/j-cb04046/index.html
http://deadprogrammersociety.blogspot.de/2006/11/ruby-domain-specific-languages-basics.html
http://deadprogrammersociety.blogspot.de/2006/11/ruby-domain-specific-languages-basics_08.html
http://deadprogrammersociety.blogspot.de/2006/11/ruby-domain-specific-languages-basics_19.html
http://deadprogrammersociety.blogspot.de/2006/11/ruby-domain-specific-languages-basics_27.html
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I work on a team that decided long ago to use Chef's template resource to make dynamic scripts to be executed in an execute reource block.
I know this feature was only built to generate config files and the like, but I have to work with what I've got here.
Basically I need to know how to write to Chef::Log from a Ruby script generated from a template block. The script is not in the same context as the cookbook that generated it, so I can't just call require 'chef/log' in the script. I also do not want to just append the chef-run.log because that runs into timing problems.
Is there any way to accomplish this as cleanly as possible without appending to chef-run.log?
Thank you for your time.
Chef::Log is a global, so technically you can just call its methods directly from inside a template, but this is really weird and you probably shouldn't. Do whatever logging you need from the recipe code instead. If you need to log some values, compute them in the recipe and them pass them in using variables.
I'm pretty new to Gradle and have to invoke a shell command and parse it's console-output.
After doing some research how to achieve this i ended up with two ways:
The Gradle-way using the task-type: Exec (org.gradle.api.tasks.Exec) with commandLine.
The Groovy/Java-way using java.lang.String with execute and java.lang.Process.
The question is, why should i use the Gradle-way over the Java-way or vice versa? I couldn't find any resource pointing out the difference, yet.
If what You need to do is a pretty standard task it's better to use Gradle's Exec. It's just a wrapper that also starts a command under the hood.
If what You're looking for is a better control or untypical command or maybe a dedicated handling of result it better to use execute() on String (but it's better to pass command as a List to avoid parser issues). It's more low level and needs more coding.
I want to store brief snippets of code in the database (following a standard signature) and "inject" them at runtime. One way would be using eval(my_code). Is there some way to debug the injected code using breakpoints, etc? (I'm using Rubymine)
I'm aware I can just log to console, etc, but I'd prefer IDE-style debugging if possible.
Hm. Let's analyze your question. Firstly, it does not seem to have anything to do with databases: You simply store a code block in the source form somewhere. It can be a file, or a database. Secondly, you don't want IDE-style "debugging", but TDD-style. (But don't concentrate on that question now.)
What you need, is assertions about your code. That is, you need to describe what output should your code produce given some input examples. And then, you need to run that code and see whether its function matches the expectations. Furthermore, if you are not sure about the source of your snippets, run them in a sandbox (with $SAFE = 4). If your code fails the expectations, raise nice errors (TypeError, or even better, your custom made exception), and then you can eg. rescue those exceptions and eg. use some default code snippets...
... but maybe I'm not actually answering the same question that you are asking. If that's the case, then let me share one link to this sourcify gem, which let's you know the source, so that you can insert a breakpoint by saying eg. require 'rdebug' in the middle of code, or can even convert code to sexps. That's all I know.
I have following cucumber test
Scenario Outline:
Given site <url> is available
Then I see all all content
Examples:
|url|
|"google.com|
In the test case is dynamic and is generated in ruby code.
Problem:
I want to replace google.com with a ruby variable e.g., <%URL%>. Is that possible to embed ruby code in cucumber tests and evaluate ?
I think you should not do that on the feature steps. If you need a ruby variable here it means that you are doing something wrong. Check some examples around
Link here
The features should be clear text so anyone can read, specially non-programmers. so that is why you should now start mixing code with features. The code goes behind, in your step definition.
You can eval this string it if you trust code in this feature file. But it may be a bad idea for the reasons outlined by #SnakeSanders.
Does anybody know of a Haskell library which can parse arbitrary Bash scripts?
A cursory search of Hackage indicates that there's a package called bash for writing scripts, but I don't see anything for parsing them.
Basically I've just had a large collection of Bash scripts dumped on me, and I'd like to do some code analysis on it. But the first stage is obviously to be able to parse this stuff.
I don't know Bash very well personally. I suppose I could sit down and wage through the volumous man-page to get the complete BNF grammar for it. (I imagine it's very complex, given the shell's long and backwards-compatible history.) I was just wondering whether somebody else has already done this work for me...
Perhaps extend language-sh.
Language.Sh is a collection of modules for parsing and manipulating
expressions in shell grammar. This is part of a larger project, shsh.
Please note that the API is somewhat unstable until we reach version
1.0.