SOLID

 SOLID

S	Single responsibility principle[4] a class should have only a single responsibility (i.e. changes to only one part of the software's specification should be able to affect the specification of the class)
O	Open/closed principle[5] “software entities … should be open for extension, but closed for modification.”
L	Liskov substitution principle[6] “objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program.” See also design by contract.
I	Interface segregation principle[7] “many client-specific interfaces are better than one general-purpose interface.”[8]
D	Dependency inversion principle[9] one should “depend upon abstractions, [not] concretions.”[8]

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