Class: Dim::Container
- Inherits:
-
Object
- Object
- Dim::Container
- Defined in:
- lib/dim.rb
Overview
Dim::Container is the central data store for registering services used for dependency injuction. Users register services by providing a name and a block used to create the service. Services may be retrieved by asking for them by name (via the [] operator) or by selector (via the method_missing technique).
Instance Attribute Summary collapse
-
#parent ⇒ Object
readonly
Returns the value of attribute parent.
Class Method Summary collapse
-
.service_block(name) ⇒ Object
Searching for a service block only reaches the Container class when all the containers in the hierarchy search chain have no entry for the service.
Instance Method Summary collapse
-
#[](name) ⇒ Object
Lookup a service by name.
-
#clear_cache! ⇒ Object
Resets the cached services.
-
#initialize(parent = nil) ⇒ Container
constructor
Create a dependency injection container.
-
#method_missing(sym, *args, &block) ⇒ Object
Lookup a service by message selector.
- #override(name, &block) ⇒ Object
-
#register(name, raise_error_on_duplicate = true, &block) ⇒ Object
Register a service named
name
. -
#register_env(name, default = nil) ⇒ Object
Lookup a service from ENV variables, or use a default if given; fall back to searching the container and its parents for a default value.
-
#service_block(name) ⇒ Object
Return the block that creates the named service.
-
#verify_dependencies(*names) ⇒ Object
Given a list of services, check to see if they are available, returning true or false.
Constructor Details
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing(sym, *args, &block) ⇒ Object
Lookup a service by message selector. A service with the same name as sym
will be returned, or an exception is thrown if no matching service is found.
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# File 'lib/dim.rb', line 108 def method_missing(sym, *args, &block) self[sym] end |
Instance Attribute Details
#parent ⇒ Object (readonly)
Returns the value of attribute parent.
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# File 'lib/dim.rb', line 47 def parent @parent end |
Class Method Details
.service_block(name) ⇒ Object
Searching for a service block only reaches the Container class when all the containers in the hierarchy search chain have no entry for the service. In this case, the only thing to do is signal a failure.
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# File 'lib/dim.rb', line 128 def self.service_block(name) fail(MissingServiceError, "Unknown Service '#{name}'") end |
Instance Method Details
#[](name) ⇒ Object
Lookup a service by name. Throw an exception if no service is found.
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# File 'lib/dim.rb', line 101 def [](name) @cache[name] ||= service_block(name).call(self) end |
#clear_cache! ⇒ Object
Resets the cached services
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# File 'lib/dim.rb', line 120 def clear_cache! @cache = {} end |
#override(name, &block) ⇒ Object
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# File 'lib/dim.rb', line 71 def override(name,&block) register(name,false,&block) end |
#register(name, raise_error_on_duplicate = true, &block) ⇒ Object
Register a service named name
. The block
will be used to create the service on demand. It is recommended that symbols be used as the name of a service.
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# File 'lib/dim.rb', line 60 def register(name,raise_error_on_duplicate = true,&block) if @services[name] && raise_error_on_duplicate fail DuplicateServiceError, "Duplicate Service Name '#{name}'" end @services[name] = block self.class.send(:define_method, name) do self[name] end end |
#register_env(name, default = nil) ⇒ Object
Lookup a service from ENV variables, or use a default if given; fall back to searching the container and its parents for a default value
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# File 'lib/dim.rb', line 85 def register_env(name,default = nil) if value = ENV[name.to_s.upcase] register(name) { value } elsif default register(name) { default } else begin @parent.service_block(name) rescue MissingServiceError raise EnvironmentVariableNotFound, "Could not find an ENV variable named '#{name.to_s.upcase}' nor could we find a service named #{name} in the parent container" end end end |
#service_block(name) ⇒ Object
Return the block that creates the named service. Throw an exception if no service creation block of the given name can be found in the container or its parents.
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# File 'lib/dim.rb', line 115 def service_block(name) @services[name] || @parent.service_block(name) end |
#verify_dependencies(*names) ⇒ Object
Given a list of services, check to see if they are available, returning true or false.
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# File 'lib/dim.rb', line 76 def verify_dependencies(*names) names.all? do |name| respond_to?(name) || service_block(name) end rescue Dim::MissingServiceError false end |