Represents an implicit set of parameters through the use of numbered parameters within a block or lambda.
-> { _1 + _2 }
^^^^^^^^^^^^^^
Represents the list of parameters on a method, block, or lambda definition.
def a(b, c, d)
^^^^^^^
end
Represents the use of the ‘^` operator for pinning an expression in a pattern matching expression.
foo in ^(bar)
^^^^^^
Represents a required keyword parameter to a method, block, or lambda definition.
def a(b: )
^^
end
Represents a required parameter to a method, block, or lambda definition.
def a(b)
^
end
Represents a rest parameter to a method, block, or lambda definition.
def a(*b)
^^
end
Represents the use of the ‘until` keyword, either in the block form or the modifier form.
bar until foo ^^^^^^^^^^^^^ until foo do bar end ^^^^^^^^^^^^^^^^^^^^
This represents an error that was encountered during parsing.
This represents the result of a call to ::parse or ::parse_file. It contains the AST, any comments that were encounters, and any errors that were encountered.
Indicates a timeout resolving a name or address.
A NotifyTemplateEntry is returned by TupleSpace#notify and is notified of TupleSpace changes. You may receive either your subscribed event or the ‘close’ event when iterating over notifications.
See TupleSpace#notify_event for valid notification types.
ts = Rinda::TupleSpace.new observer = ts.notify 'write', [nil] Thread.start do observer.each { |t| p t } end 3.times { |i| ts.write [i] }
Outputs:
['write', [0]] ['write', [1]] ['write', [2]]
Raised when trying to activate a gem, and the gem exists on the system, but not the requested version. Instead of rescuing from this class, make sure to rescue from the superclass Gem::LoadError to catch all types of load errors.
Signals that a file permission error is preventing the user from operating on the given directory.
Raised when a gem dependencies file specifies a ruby version that does not match the current version.
Raised by Resolver when a dependency requests a gem for which there is no spec.
Gem::PathSupport facilitates the GEM_HOME and GEM_PATH environment settings to the rest of RubyGems.
The Version class processes string versions into comparable values. A version string should normally be a series of numbers separated by periods. Each part (digits separated by periods) is considered its own number, and these are used for sorting. So for instance, 3.10 sorts higher than 3.2 because ten is greater than two.
If any part contains letters (currently only a-z are supported) then that version is considered prerelease. Versions with a prerelease part in the Nth part sort less than versions with N-1 parts. Prerelease parts are sorted alphabetically using the normal Ruby string sorting rules. If a prerelease part contains both letters and numbers, it will be broken into multiple parts to provide expected sort behavior (1.0.a10 becomes 1.0.a.10, and is greater than 1.0.a9).
Prereleases sort between real releases (newest to oldest):
1.0
1.0.b1
1.0.a.2
0.9
If you want to specify a version restriction that includes both prereleases and regular releases of the 1.x series this is the best way:
s.add_dependency 'example', '>= 1.0.0.a', '< 2.0.0'
Users expect to be able to specify a version constraint that gives them some reasonable expectation that new versions of a library will work with their software if the version constraint is true, and not work with their software if the version constraint is false. In other words, the perfect system will accept all compatible versions of the library and reject all incompatible versions.
Libraries change in 3 ways (well, more than 3, but stay focused here!).
The change may be an implementation detail only and have no effect on the client software.
The change may add new features, but do so in a way that client software written to an earlier version is still compatible.
The change may change the public interface of the library in such a way that old software is no longer compatible.
Some examples are appropriate at this point. Suppose I have a Stack class that supports a push and a pop method.
Switch from an array based implementation to a linked-list based implementation.
Provide an automatic (and transparent) backing store for large stacks.
Add a depth method to return the current depth of the stack.
Add a top method that returns the current top of stack (without changing the stack).
Change push so that it returns the item pushed (previously it had no usable return value).
Changes pop so that it no longer returns a value (you must use top to get the top of the stack).
Rename the methods to push_item and pop_item.
Rational Versioning Versions shall be represented by three non-negative integers, separated by periods (e.g. 3.1.4). The first integers is the “major” version number, the second integer is the “minor” version number, and the third integer is the “build” number.
A category 1 change (implementation detail) will increment the build number.
A category 2 change (backwards compatible) will increment the minor version number and reset the build number.
A category 3 change (incompatible) will increment the major build number and reset the minor and build numbers.
Any “public” release of a gem should have a different version. Normally that means incrementing the build number. This means a developer can generate builds all day long, but as soon as they make a public release, the version must be updated.
Let’s work through a project lifecycle using our Stack example from above.
Version 0.0.1
The initial Stack class is release.
Version 0.0.2
Switched to a linked=list implementation because it is cooler.
Version 0.1.0
Added a depth method.
Version 1.0.0
Added top and made pop return nil (pop used to return the old top item).
Version 1.1.0
push now returns the value pushed (it used it return nil).
Version 1.1.1
Fixed a bug in the linked list implementation.
Version 1.1.2
Fixed a bug introduced in the last fix.
Client A needs a stack with basic push/pop capability. They write to the original interface (no top), so their version constraint looks like:
gem 'stack', '>= 0.0'
Essentially, any version is OK with Client A. An incompatible change to the library will cause them grief, but they are willing to take the chance (we call Client A optimistic).
Client B is just like Client A except for two things: (1) They use the depth method and (2) they are worried about future incompatibilities, so they write their version constraint like this:
gem 'stack', '~> 0.1'
The depth method was introduced in version 0.1.0, so that version or anything later is fine, as long as the version stays below version 1.0 where incompatibilities are introduced. We call Client B pessimistic because they are worried about incompatible future changes (it is OK to be pessimistic!).
Version Catastrophe: From: www.zenspider.com/ruby/2008/10/rubygems-how-to-preventing-catastrophe.html
Let’s say you’re depending on the fnord gem version 2.y.z. If you specify your dependency as “>= 2.0.0” then, you’re good, right? What happens if fnord 3.0 comes out and it isn’t backwards compatible with 2.y.z? Your stuff will break as a result of using “>=”. The better route is to specify your dependency with an “approximate” version specifier (“~>”). They’re a tad confusing, so here is how the dependency specifiers work:
Specification From ... To (exclusive) ">= 3.0" 3.0 ... ∞ "~> 3.0" 3.0 ... 4.0 "~> 3.0.0" 3.0.0 ... 3.1 "~> 3.5" 3.5 ... 4.0 "~> 3.5.0" 3.5.0 ... 3.6 "~> 3" 3.0 ... 4.0
For the last example, single-digit versions are automatically extended with a zero to give a sensible result.
This class is responsible for generating initial code blocks that will then later be expanded.
The biggest concern when guessing code blocks, is accidentally grabbing one that contains only an “end”. In this example:
def dog begonn # mispelled `begin` puts "bark" end end
The following lines would be matched (from bottom to top):
1) end 2) puts "bark" end 3) begonn puts "bark" end
At this point it has no where else to expand, and it will yield this inner code as a block
Keeps track of what elements are in the queue in priority and also ensures that when one element engulfs/covers/eats another that the larger element evicts the smaller element
Holds elements in a priority heap on insert
Instead of constantly calling ‘sort!`, put the element where it belongs the first time around
Example:
queue = PriorityQueue.new queue << 33 queue << 44 queue << 1 puts queue.peek # => 44
Class that parses String’s into URI’s.
It contains a Hash set of patterns and Regexp’s that match and validate.