stateful example

new_stateful

x0 = (0..500).map{ |xx| xx/1000.0 }
y0 = x0.map{ |xx| Math.exp(-xx) }
x1 = (500..1000).map{ |xx| xx/1000.0 }
y1 = x1.map{ |xx| Math.exp(-xx) }

# create new datablock
datablock = Datablock.new([x0, y0])

# now data will be sent to gnuplot and new datablock in terminal created
# everything is good, we still may have stateless objects
plot = Plot.new([datablock, with: 'lines', title: 'Exp (points)'], term: ['qt', persist: true])
plot.plot # (1)

datablock.update!([x1, y1])
plot.plot # plots updated data

new_stateless

x0 = (0..500).map{ |xx| xx/1000.0 }
y0 = x0.map{ |xx| Math.exp(-xx) }
x1 = (500..1000).map{ |xx| xx/1000.0 }
y1 = x1.map{ |xx| Math.exp(-xx) }

# create new datablock
datablock = Datablock.new([x0, y0])

# now data will be sent to gnuplot and new datablock in terminal created
# everything is good, we still may have stateless objects
plot = Plot.new([datablock, with: 'lines', title: 'Exp (points)'], term: ['qt', persist: true])
plot.plot # (1)

updated_datablock = datablock.update([x1, y1])
updated_plot = plot.update_datablock(datablock, updated_datablock)
plot.plot # no problem, result is the same as in (1)
updated_plot.plot # plots updated data

old

x0 = (0..500).map{ |xx| xx/1000.0 }
y0 = x0.map{ |xx| Math.exp(-xx) }
x1 = (500..1000).map{ |xx| xx/1000.0 }
y1 = x1.map{ |xx| Math.exp(-xx) }

# create new datablock
datablock = Datablock.new([x0, y0])

# now data will be sent to gnuplot and new datablock in terminal created
# everything is good, we still may have stateless objects
plot = Plot.new([datablock, with: 'lines', title: 'Exp (points)'], term: ['qt', persist: true])
plot.plot # (1)

datablock.update([x1, y1])
plot.plot # now we have a problem: image plotted in (1) isn't the same as this one