doWhile: doWhile

In mrparker909/doWhile: Implements a doWhile loop.

Description

doWhile

Usage

doWhile(do, While = F, Return = NULL, vars = NULL)

Arguments

do	Expression to evaluate at least once. The "do" expression will be repeated until the "While" condition is FALSE.
While	Logical expression indicating the stopping condition. The doWhile loop will end when the "While" condition is no longer TRUE. Default is FALSE (execute "do" expression once and then return).
Return	Expression to evaluate and return (allows returning of variables scoped inside the doWhile function). Default is NULL.
vars	List of variables to pass by value to the doWhile loop function.

Examples

doWhile(do={k=k+1; print(k)}, While={k<5},vars=list(k=0))
doWhile({if(!exists("k")) {k<-1} else {k<-k+1}; print(k)}, {k<5})

k <<- 0
doWhile({k<<-k+1; print(k)}, {k<5})
rm(k)

# Note that i remains zero here due to scoping
i=0
doWhile(do={i=i+1; print(i)}, While={i<10}, Return=i)
print(i)

# But we can force an update of i using "i <<- i+1"
i=0
doWhile(do={i<<-i+1; print(i)}, While={i<10}, Return=i)
print(i)

# or we can declare j (and jPI) in the scope of the doWhile:
jPI=doWhile(do={if(!exists("j")|!exists("jPI")){j<-0;jPI<-0}
                else{j=j+1; jPI=jPI+pi}},
            While={j<10},
            Return={jPI})
print(jPI)

# Using a list lets us check existence just once when we have many parameters in the loop:
Y = doWhile(do    ={ if(!exists("E")) {E<-list(x=pi, y=exp(1))}; E$y=E$x+E$y},
            While ={ E$y < 100},
            Return={ E$y})
print(Y)

mrparker909/doWhile documentation built on Nov. 4, 2019, 7:35 p.m.