Creating objects with a complex constructor can be a bit of a pain in any language. One technique I have used is method chaining. It is not applicable to every type of class but it can be useful.<\/p>\n
Method chain can help simply the use class and allows more complex object initialisation without having to worry about the order of the parameters and be done inline.<\/p>\n
Consider the use of an “Account” class that takes Name, Address, Telephone and Country. All of which are strings, the constructor with four strings would not be a great constructor. <\/p>\n
So you could have a simple constructor and four properties\/methods.. however so set up the object would mean you have spread the setup over multiple lines.<\/p>\n
Using method chain you can overcome this and even space in the “value” area of the object in your storage area.<\/p>\n
The trick of the pattern is to provide methods that always return this\/self, so we can change the invokes together… For example:<\/p>\n This technique could even be used to build up a series of items required, for example, the preparation and execution of a sql statement comes to mind… in a similar fashion to Linq.<\/p>\n So… lets look at an example:<\/p>\n perform varying lAccount through accounts goback. <\/code><\/p>\n WIth the class being:<\/p>\n working-storage section. method-id New. method-id Name public. method-id Address public. method-id Telephone public. method-id Email public. method-id Country public. method-id ToString public override. Which when run with Visual COBOL gives: <\/p>\n Creating objects with a complex constructor can be a bit of a pain in any language. One technique I have used is method chaining. It is not applicable to every type of class but it can be useful. Method chain … Continue reading
\nset x to new type Account::Name(\"xx\")::Address(\"yy\") ::Telephone(\"yy\")
\n ::Country(\"zz\")::World(\"Earth\")
\n<\/code><\/p>\n
\n$set ilusing\"System.Collections.Generic\"
\nprogram-id. Program1 as \"MethodChaining1.Program1\".
\ndata division.
\nworking-storage section.
\n01 accounts type List[type Account] value new type List[type Account].
\n01 jAccount type Account value
\n new type Account::Name(\"Mr Johnson\")::Address(\"Somewhere, some place\")
\n ::Telephone(\"+44 1234 4321\").
\n01 sAccount type Account value
\n new type Account::Name(\"Mr Smith\")::Address(\"Nowhere place\")
\n ::Telephone(\"+44 1234 4321\")::Country(\"Wales\").
\n01 lAccount type Account.
\nprocedure division.
\n invoke accounts::Add(jAccount)
\n invoke accounts::Add(sAccount)<\/p>\n
\n display lAccount
\n end-perform<\/p>\n
\nend program.<\/p>\n
\nclass-id Account.<\/p>\n
\n01 wName string property as \"Name\".
\n01 wAddres string property as \"Address\".
\n01 wCountry string property as \"Country\".
\n01 wTelephone string property as \"Telephone\".
\n01 wEmail string property as \"Email\".<\/p>\n
\nlocal-storage section.
\nprocedure division.
\n set wCountry to type System.Globalization.RegionInfo::CurrentRegion::DisplayName
\nend method.<\/p>\n
\nprocedure division using uName as string
\n returning ret as type Account.
\n set self::Name to uName
\n set ret to self
\nend method.<\/p>\n
\nprocedure division using uAddress as string
\n returning ret as type Account.
\n set self::Address to uAddress
\n set ret to self
\nend method.<\/p>\n
\nprocedure division using uTelephone as string
\n returning ret as type Account.
\n set self::Address to uTelephone
\n set ret to self
\nend method.<\/p>\n
\nprocedure division using uEmail as string
\n returning ret as type Account.
\n set self::Address to uEmail
\n set ret to self
\nend method.<\/p>\n
\nprocedure division using uCountry as string
\n returning ret as type Account.
\n set self::Country to uCountry
\n set ret to self
\nend method.<\/p>\n
\nprocedure division returning ret as string.
\nset ret to String::Format(\"Name:{0}, Address:{1}, Telephone:{2}, Email:{3}, Country:{4}\",
\n self::Name, self::Address, self::Telephone,
\n self::Email, self::Country)
\nend method.
\nend class.
\n<\/code><\/p>\n
\nName:Mr Johnson, Address:+44 1234 4321, Telephone:, Email:, Country:United Kingdom
\nName:Mr Smith, Address:+44 1234 4321, Telephone:, Email:, Country:Wales
\n<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"