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In furthering my study of Ruby, I've noticed that some methods really seem to give power to the language, while others are just syntactic sugar.
Examples of sugar: .split, .strip, i.e. any methods that just make doing a menial task with a data structure easier.
Examples of power methods: call, send, responds_to?, method_missing, etc.
It seems like if you understand those "power methods" you really know the language.
Curious about three things:
Has anyone every made such a distinction, be it in a book/blog post etc?
Do you personally make such a distinction?
If you feel what I'm saying is correct, what "power methods" should I know and use better?
Thanks (hope this question doesn't get closed!)
These aren't really "power methods" but are just another tool in the toolbox that is the Ruby library.
Methods like call and send are for low-level operations, bypassing the usual Ruby semantic layer. responds_to? is often used when writing generic code that uses duck typing, and method_missing is a way of writing code that responds to a variety of methods in a dynamic way. This is how Rails ActiveRecord handles methods calls like find_by_name_or_phone automatically.
Methods like split, strip and chomp are simply data transformation methods. Their primary function is to convert one thing into another, optionally in-place.
I don't think there's a distinction between any of these methods, they're all quite useful, but they do have their particular uses. As far as Ruby is concerned, though, all methods are equal, there's no hierarchy or inherent importance to them.
Some methods you will use very infrequently, so you're less likely to ever have need for them unless you've done a lot of Ruby.
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What's the benefit of putting all my methods inside a Module?
module Math
def Math.print_message
puts "Testing 123 ..."
end
end
If I just write "print_message" in the file and then require the file from within another file, then I can call "print_message" as well.
What's the advantage of having it within this Module-end construct?
Some Things a Ruby Module Can Do for You
In many ways, modules act a lot like classes, although you can't actually instantiate them. There are quite a number of reasons to put code, classes, and other objects inside modules. These include:
Namespacing, to prevent collisions between same-named constants, classes, methods, and variables.
The ability to compose or extend classes, rather than relying on Ruby's single-inheritance model by "mixing in" modules. That's why modules in Ruby are often called mixins.
The ability define class and module level methods that don't need to be instantiated to be used.
The ability to hook the inclusion of modules to create certain behavior when you mix them into other classes.
Support for autoloading.
The ability to adjust the lookup order of the class hierarchy depending on whether you include or prepend a module.
Support for refinements (see Module#refine and Module#using).
There are likely other things that I haven't thought about in this quick, off-the-cuff answer. However, modules are essential building blocks for gems and larger Ruby applications, and understanding them is worth doing, especially if you're planning to grow beyond basic scripting with Ruby.
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As in java8:
someList.stream().map(e->e.getXXX()).toList()
For example, I have a Student array/slice, and the struct Student contains properties like Id, Name, and so on.
I want to extract all Ids into a NEW array/slice with one-line code like java8 as mentioned above, instead of range. Is there is an example?
Currently there is not an easy, builtin way to do this. Although Go has first-class functions and lexical closure, it's not possible to write a function like map that will operate on arbitrary types in the way you want. (Also, there's no compact lambda syntax, but I consider that a relatively minor issue).
Instead, you have to do one of the following:
Operate on interface{}. While this would let you write a func map([]interface{}, func(interface{})interface{}) []interface{}, you lose compile-time type safety, you lose performance, and a []interface{} is not a []string (or whatever the type is of the field you wanted to fetch), nor can you even type-assert it to one, so working with the result is cumbersome.
Use code-generation. There are libraries out there that will generate map/filter/etc. code for you, specialized to given types, so that none of the disadvantages of #1 apply. And Go ships with a Go parser in the standard library, so most code generators are fairly robust. But code generation is a separate build step, hampers debuggability, and can hurt the clarity of code.
Just live with boilerplate, writing lots of loops, and forget about trying to achieve functional style.
Wait for Go 1.18 to bring generics, which should make libraries of functional idioms a lot more practical.
Most experienced Go users would recommend approach #3, and so do I (reluctantly).
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So, I am getting into Ruby. I'm learning it everyday. And just like Spanish. I am getting able to read it, but not write it.
I am doing "Ruby the Hard Way" and I understand WHY things work, but the more I move through it the more I realize that I could not mimic the code if someone just came up to me and said "I need you to do so and so in Ruby."
I know that it is going to depend largely on what the task is, is how my code will be set up. But are there any tips and/or tricks for Ruby. (i.e. "Always write your variables first or strings before arrays" or something like that.
I'm unclear on when to write which lines of code or WHY something has to be below another block of code. I am aware of the nebulous nature of this question, but I'm looking for a bit of more broad rules for Ruby.
I think the WHY in your question has to do with learning the concepts, but not really applying them in a way that's meaningful to you.
I'd recommend finding a task you can accomplish with Ruby. Eg: write to a file, get content out of a webpage, get the date/time in a specific country, whatever. Start small, but challenge yourself. Look at StackOverflow ruby tag, or Github to see what other people are doing with Ruby.
That will get you thinking about the problem you're solving, and not the code alone; which is what programming is all about.
Then come back here and ask about the specifics you're struggling with.
Small disclaimer: yes, all of the above is my opinion; and as others have commented, this question is too broad.
The question is really too broad. I'll suppose that you know of another language already. If you are looking for code convention, look at the Ruby Style Guide. Taking courses at Code School could get you an idea of the good practice (and make you learn useful frameworks like Rails. Reading "The Ruby Way" can give you a feeling of the "pulse" of the language. Building the blog application used by many Rails book could also help.
Finally, checkout sample Rails or Ruby projects from GitHub.
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What do you think fellow programmers about using short functions vs using inline code?
Example with function:
//Check if all keys from $keys exist in $array
function functionName(array $array, array $keys) {
return array_diff($keys, array_keys($array));
}
functionName($mas,$keys);
vs. using just the code:
array_diff($keys, array_keys($mas));
I think that in your example, it's superfluous. There's no need to create an extra function call and add bytes to the filesize without good reason.
Also, the inline array_diff($keys, array_keys($mas)); is a lot easier to debug for fellow programmers, than looking through your code to find out exactly what functionName() does and where it is located.
It depends on what functionName actually is.
If you're using customerDetailsAreValid throughout your code and you suddenly have to add validation of $array['email'], you're going to be grateful for the separation of intent and implementation.
If on the other hand you're wrapping array_diff in the function diffArray there isn't much point.
I think clarity is a prime concern when writing logic you hope will be around for any amount of time.
In general, I abhor inline functions. I think they are lazy, promote spaghetti code, and in general exude a complete lack of concern for style/readability/clarity on the part of the developer.
Filesize - I find this argument very arbitrary. The js files are transmitted once and then cahced. In many cases, you find descriptive names, etc, (hopefully comments) that all add to file size. If size is very important , use a file minimizer that makes a file as tiny as possible.
Looking for a function? How about trying to figure out exactly what is going on in a voluminous docReady. CTL-F usually invokes a find facility.
I will grant that there can be simple cases where an inline function detracts little from the readability of the code. However, the inline approach will never be MORE CLEAR than the alternate separation of reference and implementation.
my two cents
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I'd like to write a code beautifier and i thought of using Ruby to do it. Could someone show me a place to get started? I've seen a lot of code beautifiers online but I've never come across any tutorials on how to write one. Is this a very challenging task for someone who's never undertaken any projects such as writing a compiler, parser, etc. before?
(Is there another langauge which would be more well suited for this kind of task, excluding C/C++?)
Python has an interesting feature - it exposes its own parser to scripts. There are examples that use the AST - abstract syntax tree - and do the pretty printing.
I'm not aware that Ruby exposes its own parser to its scripts in such a way, but there are parsers for Ruby written in Ruby here.
Well... I think the initial steps are what you'd do for any project.
Write a list of requirements.
Describe a user interface to your program, that you like and won't prevent you meeting those requirements.
Now you can write down more of a "code" design, and pick the language that would be easiest for you to meet that design.
Here's some requirements off the top of my head:
Supports code beautifying of these languages: Ruby, Python, Perl
Output code behaves identically to input
Output has consistent use of tabs/spaces
Output has consistent function naming convention
Output has consistent variable naming convention
Output has matching braces and indentation
Make as many as you want, it's your program. ;p I was kidding about the Perl, but I think every language you support is going to add a more work.