https://github.com/rdnewman/loba
Easy tracing for debugging. Handy methods for adding trace lines to output or Rails logs.
https://github.com/rdnewman/loba
debugging-tool gem ruby ruby-gem
Last synced: 11 months ago
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Easy tracing for debugging. Handy methods for adding trace lines to output or Rails logs.
- Host: GitHub
- URL: https://github.com/rdnewman/loba
- Owner: rdnewman
- License: mit
- Created: 2015-12-30T02:48:05.000Z (over 10 years ago)
- Default Branch: main
- Last Pushed: 2024-09-09T17:09:44.000Z (almost 2 years ago)
- Last Synced: 2025-04-08T05:12:52.295Z (about 1 year ago)
- Topics: debugging-tool, gem, ruby, ruby-gem
- Language: Ruby
- Homepage:
- Size: 192 KB
- Stars: 5
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Security: SECURITY.md
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README
# Loba
[](https://badge.fury.io/rb/loba)
[](https://github.com/rdnewman/loba/actions?query=branch%3Amain++)
[](https://codeclimate.com/github/rdnewman/loba)
[](https://codeclimate.com/github/rdnewman/loba/coverage)
Easy tracing for debugging: handy methods for adding trace lines to output (or logs).
(Installation is pretty much what you'd expect for a gem, but read Environment Notes below first.)
## Overview
There are two kinds of questions I usually want to answer when trying to diagnose code behavior:
1. Is this spot of code being reached (or is it reached in the order I think it is)?
1. What is the value of this variable?
Loba statements are intended to be terse to minimize typing.
Loba statements are intended to be minimally invasive and atomic. They should have negligible impact over regular `puts` or logging statements.
Loba statements are expected to be removed when you're done with them. No point in cluttering up production code.
Loba will generally always write to `$stdout` (i.e., `puts`). In addition to `$stdout`, Loba can also be made to write to a log (:debug). Writing to `$stdout` can be overridden.
Loba will work equally well with or without Rails. If Rails is present and writing to a log is wanted, it will use the Rails log (e.g., `Rails.logger.debug`).
Loba uses the [rainbow gem](https://rubygems.org/gems/rainbow) to help make trace statements more visible.
## Usage
Aligning Loba statements to the far left in your source code (a la `=begin` or `=end`) will make them easier to see and remove when you're done. You may though find this somewhat annoying to do if your editor auto-indents.
#### Timestamp notices: `Loba.ts`
Outputs a timestamped notice, useful for quick traces to see the code path and easier than, say, [Kernel#set_trace_func](http://ruby-doc.org/core-2.2.3/Kernel.html#method-i-set_trace_func). Also does a simple elapsed time check since the previous timestamp notice to help with quick, minimalist profiling.
For example,
```text
[TIMESTAMP] #=0002, diff=93.478016, at=1451444972.970602 (in=/home/usracct/src/myapp/app/models/target.rb:55:in `some_calculation')
```
To invoke,
```ruby
Loba.ts # or with optional keyword arguments
```
`Loba.timestamp` is an alias for `Loba.ts`.
You can read [more detail](readme/ts.md) on this command.
#### Variable or method return inspection: `Loba.val`
Writes line to `$stdout` (or optionally to a log, `logger.debug`) showing value with method and class identification.
```ruby
Loba.val :var_sym # the :var_sym argument is the variable or method name given as a symbol
```
For example,
```text
[Target.some_calculation] my_var: 54 (in /home/usracct/src/myapp/app/models/target.rb:55:in `some_calculation')
```
You can read [more detail](readme/val.md) on this command.
#### Output and logging options
There are several options to control where Loba writes its output:
* `out`: controls whether `puts` to `$stdout` occurs (default: `true`)
* `log`: controls whether logging occurs (default: `false`)
* `logger`: controls which logger is used
* `logdev`: in non-Rails environments, another way to direct where logging occurs
You can read [more detail](readme/log.md) about how to use these options.
#### Snippet example
```ruby
require 'loba' # not generally necessary in Rails projects
class HelloWorld
def initialize
@x = 42
Loba.ts # Loba statement put to the far left as a reminder to remove when done
@y = "Charlie"
end
def hello
Loba.val :@x
puts "Hello, #{@y}" if @x == 42
Loba.ts
end
end
HelloWorld.new.hello
```
Output:
```text
[TIMESTAMP] #=0001, diff=0.000463, at=1451615389.505411 (in=/home/usracct/src/lobademo/hello_world.rb:4:in 'initialize'
[HelloWorld#hello] @x: 42 (in /home/usracct/src/loba/spec/hello_world.rb:9:in `hello')
Hello, Charlie
[TIMESTAMP] #=0002, diff=0.000720, at=1451615389.506132 (in=/home/usracct/src/lobademo/hello_world.rb:11:in 'hello'
```
## Environment Notes
This section is only relevant in Rails environments.
The expectation is that Loba statements are just for development or test trace statements. Generally, it's a bad idea to leave diagnostic code in Rails production; still, it can happen. And, occasionally, it can be useful to have trace statements in production too if you have an issue that is difficult to reproduce.
`Loba.ts` and `Loba.val` try to protect against timestamp or value notice requests being accidentally left in the code by checking for the Rails environment Loba is being invoked under. If in production, `Loba.ts` and `Loba.val` will normally just return immediately without attempting to render anything to help minimize any impact on production code.
However, that behavior can be overridden by using the option `production: true` as an additional argument to output a notice even when in the production environment. Note also behavior of the `log` option, which defaults to `false` (introduced in v2.0.0). In general, enabling in production should not be done, but we're consenting adults.
WARNING: this gem depends on the [binding_of_caller gem](https://rubygems.org/gems/binding_of_caller) -- use `production: true` with their warning in mind:
> **Recommended for use only in debugging situations. Do not use this in production apps.**
These considerations also have an impact on how you install the Loba gem when using `bundler`. If you only install the gem for `:development` and `:test`, then any Loba statements left in the code when it goes to production will cause an error because the statements wouldn't be recognized. That can be a good thing if you never want them left in.
If you simply install the gem for all environments, then Loba will be available in production, but you may not notice as easily if some Loba calls are unintentionally left in. Of course, if you want Loba statements to possibly work in production, then you should install the gem for all environments.
The following is the code example snippet but always logging even in Rails production environments:
```ruby
class HelloWorld
def initialize
@x = 42
Loba.ts log: true, production: true
@y = "Charlie"
end
def hello
Loba.val :@x, log: true, production: true
puts "Hello, #{@y}" if @x == 42
Loba.ts true
end
end
HelloWorld.new.hello
```
## Installation
See above Environment Notes if using with Rails.
Install as below to be generally available (recommended to restrict to only local use):
```bash
gem install loba
```
To bundle, add this line to your application's Gemfile:
```ruby
group :development, :test do
gem 'loba', require: false
end
```
or for all environments (for example, if `production: true` used):
```ruby
gem 'loba', require: false
```
And then execute:
```bash
bundle install
```
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run `bundle exec rake install`.
To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
## Changelog
See [CHANGELOG.md](CHANGELOG.md) for details. This gem follows semantic versioning.
## Contributing
Bug reports and pull requests are welcome on GitHub at . This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).