Class: Alf::Aggregator::Sum
- Inherits:
-
Alf::Aggregator
- Object
- Alf::Aggregator
- Alf::Aggregator::Sum
- Defined in:
- lib/alf/aggregator/sum.rb
Overview
Defines a `sum()` aggregation operator.
Example:
# direct ruby usage
Alf::Aggregator.sum{ qty }.aggregate(...)
# lispy
(summarize :supplies, [:sid], :total => sum{ qty })
Instance Attribute Summary
Attributes inherited from Alf::Aggregator
Instance Method Summary collapse
-
#_happens(memo, val) ⇒ Object
Aggregates on a tuple occurence through `memo + val`.
-
#least ⇒ Object
Returns 0 as least value.
Methods inherited from Alf::Aggregator
#==, #aggregate, coerce, #default_options, #finalize, #happens, #has_source_code!, #infer_type, inherited, #initialize, #to_lispy
Methods included from Support::Registry
#each, #listen, #listeners, #register, #registered
Constructor Details
This class inherits a constructor from Alf::Aggregator
Instance Method Details
#_happens(memo, val) ⇒ Object
Aggregates on a tuple occurence through `memo + val`
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# File 'lib/alf/aggregator/sum.rb', line 26 def _happens(memo, val) memo + val end |
#least ⇒ Object
Returns 0 as least value.
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# File 'lib/alf/aggregator/sum.rb', line 19 def least() 0 end |