module Sequel::Plugins

Empty namespace that plugins should use to store themselves, so they can be loaded via Model.plugin.

Plugins should be modules with one of the following conditions:

A singleton method named apply, which takes a model, additional arguments, and an optional block. This is called the first time the plugin is loaded for this model (unless it was already loaded by an ancestor class), before including/extending any modules, with the arguments and block provided to the call to Model.plugin.
A module inside the plugin module named ClassMethods, which will extend the model class.
A module inside the plugin module named InstanceMethods, which will be included in the model class.
A module inside the plugin module named DatasetMethods, which will extend the model’s dataset.
A singleton method named configure, which takes a model, additional arguments, and an optional block. This is called every time the Model.plugin method is called, after including/extending any modules.

Constants

SEQUEL_METHOD_NAME: Return a unique method name symbol for the given suffix.

Public Class Methods

Source

   # File lib/sequel/model/plugins.rb
61 def self.after_set_dataset(mod, meth)
62   mod.send(:define_method, :set_dataset) do |*a|
63     r = super(*a)
64     # Allow calling private class methods as methods this specifies are usually private
65     send(meth)
66     r
67   end
68 end

Add method to mod that overrides set_dataset to call the method afterward.

Calls superclass method

def_dataset_methods (mod, meths)

Source

   # File lib/sequel/model/plugins.rb
31 def self.def_dataset_methods(mod, meths)
32   Array(meths).each do |meth|
33     mod.class_eval("def #{meth}(*args, &block); dataset.#{meth}(*args, &block) end", __FILE__, __LINE__)
34     # :nocov:
35     mod.send(:ruby2_keywords, meth) if respond_to?(:ruby2_keywords, true)
36     # :nocov:
37   end
38 end

In the given module mod, define methods that are call the same method on the dataset. This is designed for plugins to define dataset methods inside ClassMethods that call the implementations in DatasetMethods.

This should not be called with untrusted input or method names that can’t be used literally, since it uses class_eval.

def_sequel_method (model, meth, expected_arity, &block)

Source

    # File lib/sequel/model/plugins.rb
 92 def self.def_sequel_method(model, meth, expected_arity, &block)
 93   if meth.is_a?(String)
 94     meth = SEQUEL_METHOD_NAME.call(meth)
 95   end
 96   call_meth = meth
 97 
 98   unless block.lambda?
 99     required_args, optional_args, rest, keyword = _define_sequel_method_arg_numbers(block)
100 
101     if keyword == :required
102       raise Error, "cannot use block with required keyword arguments when calling define_sequel_method with expected arity #{expected_arity}"
103     end
104 
105     case expected_arity
106     when 0
107       unless required_args == 0
108         # SEQUEL6: remove
109         Sequel::Deprecation.deprecate("Arity mismatch in block passed to define_sequel_method. Expected Arity 0, but arguments required for #{block.inspect}. Support for this will be removed in Sequel 6.")
110         b = block
111         block = lambda{instance_exec(&b)} # Fallback
112       end
113     when 1
114       if required_args == 0 && optional_args == 0 && !rest
115         # SEQUEL6: remove
116         Sequel::Deprecation.deprecate("Arity mismatch in block passed to define_sequel_method. Expected Arity 1, but no arguments accepted for #{block.inspect}.  Support for this will be removed in Sequel 6.")
117         temp_method = SEQUEL_METHOD_NAME.call("temp")
118         model.class_eval("def #{temp_method}(_) #{meth =~ /\A\w+\z/ ? "#{meth}_arity" : "send(:\"#{meth}_arity\")"} end", __FILE__, __LINE__)
119         model.send(:alias_method, meth, temp_method)
120         model.send(:undef_method, temp_method)
121         model.send(:private, meth)
122         meth = :"#{meth}_arity"
123       elsif required_args > 1
124         # SEQUEL6: remove
125         Sequel::Deprecation.deprecate("Arity mismatch in block passed to define_sequel_method. Expected Arity 1, but more arguments required for #{block.inspect}.  Support for this will be removed in Sequel 6.")
126         b = block
127         block = lambda{|r| instance_exec(r, &b)} # Fallback
128       end
129     else
130       raise Error, "unexpected arity passed to define_sequel_method: #{expected_arity.inspect}"
131     end
132   end
133 
134   model.send(:define_method, meth, &block)
135   model.send(:private, meth)
136   model.send(:alias_method, meth, meth)
137   call_meth
138 end

Define a private instance method using the block with the provided name and expected arity. If the name is given as a Symbol, it is used directly. If the name is given as a String, a unique name will be generated using that string. The expected_arity should be either 0 (no arguments) or 1 (single argument).

If a block with an arity that does not match the expected arity is used, a deprecation warning will be issued. The method defined should still work, though it will be slower than a method with the expected arity.

Sequel only checks arity for regular blocks, not lambdas. Lambdas were already strict in regards to arity, so there is no need to try to fix arity to keep backwards compatibility for lambdas.

Blocks with required keyword arguments are not supported by this method.

inherited_instance_variables (mod, hash)

Source

   # File lib/sequel/model/plugins.rb
43 def self.inherited_instance_variables(mod, hash)
44   mod.send(:define_method, :inherited_instance_variables) do ||
45     super().merge!(hash)
46   end
47   mod.send(:private, :inherited_instance_variables)
48 end

Add method to mod that overrides inherited_instance_variables to include the values in this hash. These affects how class instance variables will be treated during subclassing.

Calls superclass method

model_instance_variables (mod, *ivs)

Source

   # File lib/sequel/model/plugins.rb
52 def self.model_instance_variables(mod, *ivs)
53   mod.send(:define_method, :each_model_instance_variable) do |&block|
54     super(&block)
55     ivs.each(&block)
56   end
57   mod.send(:private, :each_model_instance_variable)
58 end

Sets the model instance variables used by the plugin. These instance variables will be initialized to nil for created model objects.

Calls superclass method

Private Class Methods

_define_sequel_method_arg_numbers (callable)

Source

    # File lib/sequel/model/plugins.rb
144 def self._define_sequel_method_arg_numbers(callable)
145   optional_args = 0
146   rest = false
147   keyword = false
148   callable.parameters.map(&:first).each do |arg_type, _|
149     case arg_type
150     when :opt
151       optional_args += 1
152     when :rest
153       rest = true
154     when :keyreq
155       keyword = :required
156     when :key, :keyrest
157       keyword ||= true
158     else
159       raise Error, "invalid arg_type passed to _define_sequel_method_arg_numbers: #{arg_type}"
160     end
161   end
162   arity = callable.arity
163   if arity < 0
164     arity = arity.abs - 1
165   end
166   required_args = arity
167   arity -= 1 if keyword == :required
168 
169   # callable currently is always a non-lambda Proc
170   optional_args -= arity
171 
172   [required_args, optional_args, rest, keyword]
173 end

Return the number of required argument, optional arguments, whether the callable accepts any additional arguments, and whether the callable accepts keyword arguments (true, false or :required).