:toc: macro :toclevels: 5 :figure-caption!: = Pragmater A command line interface that does one thing well by being entirely focused on managing/formatting source file https://en.wikipedia.org/wiki/Directive_(programming)[directive pragmas] (a.k.a. _magic comments_). Examples: [source,ruby] ---- #! /usr/bin/env ruby # frozen_string_literal: true # encoding: UTF-8 ---- With https://www.ruby-lang.org/en/news/2015/12/25/ruby-2-3-0-released[Ruby 2.3.0], frozen strings are supported via a pragma. This gem provides an easy way to insert or remove pragmas to single or multiple Ruby source files in order to benefit from improved memory and concurrency performance. toc::[] == Features * Supports inserting a pragma or multiple pragmas to single or multiple source files. * Supports removing pragma(s) from single or multiple source files. * Supports file list filtering. Defaults to any file. * Ensures duplicate pragmas never exist. * Ensures pragmas are consistently formatted. == Requirements . https://www.ruby-lang.org[Ruby] == Setup To install, run: [source,bash] ---- gem install pragmater ---- == Usage === Command Line Interface (CLI) From the command line, type: `pragmater --help` .... USAGE: -c, --config ACTION Manage gem configuration: edit or view. -h, --help Show this message. -i, --insert [PATH] Insert pragmas. Default: ".". -r, --remove [PATH] Remove pragmas. Default: ".". -v, --version Show gem version. OPTIONS: --comments a,b,c Add pragma comments. Default: []. --includes a,b,c Add include patterns. Default: []. .... Both the `--insert` and `--remove` commands support the same options for specifying pragmas and/or included files. Example: [source,bash] ---- pragmater --insert --comments "# frozen_string_literal: true" --includes "Gemfile" "Guardfile" "Rakefile" ".gemspec" "config.ru" "bin/**/*" "**/*.rake" "**/*.rb" ---- The `--insert` and `--remove` commands default to the current working directory so a path isn’t necessary unless you want to run Pragmater in a directory structure other than your current working directory. === Customization This gem can be configured via a global configuration: `$HOME/.config/pragmater/configuration.yml` It can also be configured via link:https://www.alchemists.io/projects/xdg[XDG] environment variables. The default configuration is as follows: [source,yaml] ---- :comments: [] :includes: [] :root_dir: "." ---- Feel free to take the above configuration, modify, and save as your own custom `configuration.yml`. The `configuration.yml` file can be configured as follows: * `comments`: Defines the array of pragmas you want to insert into your source files. Whatever is defined here will be the default used for insert and remove operations. * `includes`: Defines the array file patterns to apply to. Whatever is defined here will be the default used for insert and remove operations. * `root_dir`: Defines the root directory to apply the `includes` patterns too. By default, this will be the current directory you are running Pragmater from but can be a different directory entirely. === Available Pragmas With Ruby 2.3 and higher, the following pragmas are available: * `# encoding:` Defaults to `UTF-8` but any supported encoding can be used. For a list of values, launch an IRB session and run `Encoding.name_list`. * `# coding:` The shorthand for `# encoding:`. Supports the same values as mentioned above. * `# frozen_string_literal:` Defaults to `false` but can take either `true` or `false` as a value. When enabled, Ruby will throw errors when strings are used in a mutable fashion. * `# warn_indent:` Defaults to `false` but can take either `true` or `false` as a value. When enabled, and running Ruby with the `-w` option, it’ll throw warnings for code that isn’t indented by two spaces. === Syntax The pragma syntax allows for two kinds of styles. Example: [source,ruby] ---- # encoding: UTF-8 # -*- encoding: UTF-8 -*- ---- Only the former syntax is supported by this gem as the latter syntax is more verbose and requires additional typing. === Precedence When different multiple pragmas are defined, they all take precedence: [source,ruby] ---- # encoding: binary # frozen_string_literal: true ---- In the above example, both _binary_ encoding and _frozen string literals_ behavior will be applied. When defining multiple pragmas that are similar, behavior can differ based on the _kind_ of pragma used. The following walks through each use case so you know what to expect: [source,ruby] ---- # encoding: binary # encoding: UTF-8 ---- In the above example, only the _binary_ encoding will be applied while the _UTF-8_ encoding will be ignored (same principle applies for the `coding` pragma too). [source,ruby] ---- # frozen_string_literal: false # frozen_string_literal: true ---- In the above example, frozen string literal support _will be enabled_ instead of being disabled. [source,ruby] ---- # warn_indent: false # warn_indent: true ---- In the above example, indentation warnings _will be enabled_ instead of being disabled. === Frozen String Literals Support for frozen string literals was added in Ruby 2.3.0. The ability to freeze strings within a source can be done by placing a frozen string pragma at the top of each source file. Example: [source,ruby] ---- # frozen_string_literal: true ---- This is great for _selective_ enablement of frozen string literals but might be too much work for some (even with the aid of this gem). As an alternative, frozen string literals can be enabled via the following Ruby command line option: .... --enable=frozen-string-literal .... It is important to note that, once enabled, this freezes strings program-wide – It’s an all or nothing option. Regardless of whether you leverage the capabilities of this gem or the Ruby command line option mentioned above, the following Ruby command line option is available to aid debugging and tracking down frozen string literal issues: .... --debug=frozen-string-literal .... Ruby 2.3.0 also added the following methods to the `String` class: * `String#+@`: Answers a duplicated, mutable, string if not already frozen. Example: + [source,ruby] ---- immutable = "test".freeze mutable = +immutable mutable.frozen? # false mutable.capitalize! # "Test" ---- * `String#-@`: Answers a immutable string if not already frozen. Example: + [source,ruby] ---- mutable = "test" immutable = -mutable immutable.frozen? # true immutable.capitalize! # FrozenError ---- You can also use the methods, shown above, for variable initialization. Example: [source,ruby] ---- immutable = -"test" mutable = +"test" immutable.frozen? # true mutable.frozen? # false ---- 💡 The use of `+String#-@+`, specifically, was http://bit.ly/2DGAjgG[enhanced in Ruby 2.5.0] to _deduplicate_ all instances of the same string thus reducing your memory footprint. This can be valuable in situations where you are not using the frozen string comment and need to selectively freeze strings. === Consistency As an added bonus, this gem ensures pragmas for all analyzed files are formatted in a consistent style. This means there is always a space after the octothorpe (`#`). Here are multiple pragmas presented together for a visual comparison: [source,ruby] ---- #! /usr/bin/env ruby # encoding: UTF-8 # coding: UTF-8 # frozen_string_literal: true # warn_indent: true ---- One oddity to the above is the use of `# !/usr/bin/env ruby` is not allowed but `#! /usr/bin/env ruby` is which is why spacing is slightly different for shell pragmas. == Development To contribute, run: [source,bash] ---- git clone https://github.com/bkuhlmann/pragmater cd pragmater bin/setup ---- You can also use the IRB console for direct access to all objects: [source,bash] ---- bin/console ---- == Tests To test, run: [source,bash] ---- bin/rake ---- == link:https://www.alchemists.io/policies/license[License] == link:https://www.alchemists.io/policies/security[Security] == link:https://www.alchemists.io/policies/code_of_conduct[Code of Conduct] == link:https://www.alchemists.io/policies/contributions[Contributions] == link:https://www.alchemists.io/projects/pragmater/versions[Versions] == link:https://www.alchemists.io/community[Community] == Credits * Built with link:https://www.alchemists.io/projects/gemsmith[Gemsmith]. * Engineered by link:https://www.alchemists.io/team/brooke_kuhlmann[Brooke Kuhlmann].