begintemplate Gap
public src, target, g, valid, pr, set_gm, gm, cm
objref srcsec, targetsec, cm, gm, y, b, xvec, sl, lm, this, fih
strdef tstr

proc init(){
	g_ = 10
	valid_ = 0
	cm = new Matrix(2,2,2)
	gm = new Matrix(2,2)
	y = new Vector(2)
	b = new Vector(2)
	xvec = new Vector(2)
}

func src() {
	srcsec = new SectionRef()
	xvec.x[0] = $1
	valid_ = 0
	return valid()
}

func target() {
	targetsec = new SectionRef()
	xvec.x[1] = $1
	valid_ = 0
	return valid()
}

func g() {
	if (numarg() > 0) {
		g_ = $1
		if (valid_) {
			set_gm()
		}
	}
	return g_
}

proc set_gm() { local us, a// conductance in nanosiemens
	if (valid_ == 0) { return }
	us = .001*g_
	srcsec.sec { a = 100/area(xvec.x[0]) }
	gm.x[0][0] = us*a
	gm.x[0][1] = -us*a
	targetsec.sec { a = 100/area(xvec.x[1]) }
	gm.x[1][1] = us*a
	gm.x[1][0] = -us*a
}

func valid() {
	if (valid_ == 0) {
		if (object_id(srcsec) && object_id(targetsec)) {
			mkgap()		
		}
	}
	return valid_
}

proc mkgap() {
	sl = new SectionList()
	srcsec.sec sl.append()
	targetsec.sec sl.append()
	valid_ = 1
	set_gm()
	lm = new LinearMechanism(cm, gm, y, b, sl, xvec)
	// only necessary because we anticpate changes in diameter
	// fih = new FInitializeHandler(0, "set_gm()")
	// unfortunately up through the  5.6 2004/02/09 Main (44)
	// version there is an error in parsing the third arg, so
	sprint(tstr, "%s.set_gm()", this)
	fih = new FInitializeHandler(0, tstr)
}

proc pr() {
	if (valid_) {
srcsec.sec printf("%s %s(%g)", this, secname(), xvec.x[0])
targetsec.sec printf("---%s(%g) \tg = %g (ns)\n", secname(), xvec.x[1], g())
	}else{
		printf("%s not used\n", this)
	}
}
endtemplate Gap