yield and iterator - practical example

Parallelism example from a Well House Consultants training course
More on Parallelism [link]

This example is described in the following article(s):
• Processing data line by line - iterator in Ruby with yield - [link]

Source code: feeder Module: R112

# yield and iterator - practical example

# An iterator that generates data one line at a time

def stepthrough(source)
        fh = File.new source
        fh.each_line do |record|
                if record =~ /option247/
                        yield record
                        puts $.
                end
        end
end

# An action routine that handles each line

def report(line)
        fol = line.chomp.split(" ")
        puts "#{fol[1]} #{fol[6]} #{fol[8]}"
end

# The glue that holds them together

c = 0
stepthrough("ac_20160516") { |item|
        report item
        c += 1 }

puts "#{c} matches"
puts $.

# Sample output

__END__

WomanWithCat:4c grahamellis$ ruby feeder
option247.uk /bususer_wilts_20160404.pdf 200
2531
option247.uk /robots.txt 200
4565
option247.uk /O247images/facebook.png 200
4568
option247.uk /O247images/3.jpg 200
5392
option247.uk /O247images/4.jpg 200
5719
option247.uk /O247images/woman4.jpg 200
6030
option247.uk /O247images/2.jpg 200
6766
option247.uk /O247images/O247sidebar.jpg 200
7076
option247.uk /O247images/twitter.png 200
7246
option247.uk /O247images/man3.jpg 200
8135
option247.uk /css/multiColumnTemplate.css 200
8243
option247.uk /already.html 200
8251
option247.uk /robots.txt 200
8271
option247.uk /option6.pdf 200
8275
option247.uk /robots.txt 200
8692
option247.uk /O247images/bbcwiltshire.jpeg 200
8920
option247.uk /robots.txt 200
8939
option247.uk /standby.html 200
8940
option247.uk /O247images/woman1.jpg 200
8980
option247.uk /robots.txt 200
9002
option247.uk / 200
9004
option247.uk /O247images/1.jpg 200
9114
option247.uk /faq.html 200
9435
option247.uk /faqextra.html 200
9436
option247.uk /o247_20160407.pdf 200
9452
option247.uk /designatedbuses.pdf 200
9453
option247.uk /outline.html 200
9457
option247.uk / 200
9459
option247.uk /management.html 200
9460
option247.uk /247presentation_20160414.pdf 200
9461
option247.uk /bususer_wilts_20160404.pdf 200
9462
option247.uk /robots.txt 200
9513
option247.uk /techschemedraft.pdf 304
9514
option247.uk /O247images/melkshamnews.png 200
9636
option247.uk /O247images/man2.jpg 200
12537
option247.uk /favicon.ico 200
12814
option247.uk /O247images/email.png 200
13849
option247.uk / 200
14012
option247.uk / 200
14369
option247.uk /apple-touch-icon-precomposed.png 404
14370
option247.uk /apple-touch-icon.png 404
14372
option247.uk / 200
14373
option247.uk /apple-touch-icon-precomposed.png 404
14374
option247.uk /apple-touch-icon.png 404
14375
option247.uk /robots.txt 200
14889
option247.uk /robots.txt 200
14890
option247.uk /robots.txt 200
14892
option247.uk / 200
14893
option247.uk /hopalong.pdf 200
14895
option247.uk /people.html 200
14896
option247.uk /faq.txt 200
14897
option247.uk /robots.txt 200
15408
option247.uk / 200
15409
option247.uk /robots.txt 200
15681
option247.uk /management.html 200
15683
option247.uk / 200
17122
option247.uk /option2.pdf 200
18843
option247.uk /video.html 200
19018
option247.uk /links.html 200
19019
option247.uk /faqindex.html 200
19021
option247.uk /rg_twsw_20160121.pdf 200
19377
option247.uk /local-bus-market-study-access.pdf 200
20205
option247.uk / 200
20745
option247.uk /faqextra.html 200
20746
option247.uk /css/multiColumnTemplate.css 200
22368
option247.uk / 200
23234
option247.uk /css/multiColumnTemplate.css 200
23235
option247.uk /O247images/O247sidebar.jpg 200
23237
option247.uk /O247images/facebook.png 200
23238
option247.uk /O247images/email.png 200
23239
option247.uk /O247images/bbcwiltshire.jpeg 200
23240
option247.uk /O247images/melkshamnews.png 200
23241
option247.uk /O247images/4.jpg 200
23250
option247.uk /O247images/woman1.jpg 200
23254
option247.uk /O247images/twitter.png 200
23255
option247.uk /O247images/1.jpg 200
23256
option247.uk /O247images/3.jpg 200
23257
option247.uk /O247images/man2.jpg 200
23260
option247.uk /O247images/2.jpg 200
23263
option247.uk /O247images/man3.jpg 200
23264
option247.uk /O247images/woman4.jpg 200
23267
option247.uk /favicon.ico 200
23277
option247.uk /option1.pdf 200
23415
option247.uk /option1.pdf 200
23420
option247.uk /option3.pdf 200
23524
option247.uk /option3.pdf 200
23545
option247.uk /o247_2.pdf 200
23597
option247.uk /o247_2.pdf 200
23693
option247.uk / 200
23785
option247.uk /apple-touch-icon-precomposed.png 404
23786
option247.uk /apple-touch-icon.png 404
23787
option247.uk / 200
23788
option247.uk /apple-touch-icon-precomposed.png 404
23789
option247.uk /apple-touch-icon.png 404
23790
option247.uk /subsidised_summer_2015.pdf 200
25283
option247.uk /commercialbusmap.jpg 200
26045
option247.uk /rarebusmap.pdf 200
28595
option247.uk /robots.txt 200
28620
option247.uk /outline.html 200
28622
option247.uk /people.html 200
28623
option247.uk /faq.html 200
28837
option247.uk /O247images/twitter.png 200
28881
option247.uk /robots.txt 200
29447
option247.uk /outline.html 200
29448
option247.uk /robots.txt 200
30467
option247.uk /contact.html 200
30474
option247.uk /faq.html 200
30480
option247.uk /index.html 200
30487
option247.uk /links.html 200
30490
option247.uk / 200
31314
option247.uk /robots.txt 200
31501
option247.uk /contact.html 200
31502
option247.uk /robots.txt 200
31668
option247.uk /already.html 200
31669
option247.uk /Service_x72_web.pdf 200
32079
option247.uk /robots.txt 200
32795
option247.uk /cpm_mlm.pdf 304
32811
option247.uk /robots.txt 200
34602
option247.uk / 200
34692
option247.uk /Service_x72_web.pdf 200
39657
option247.uk /subsidised_summer_2015.pdf 200
41278
option247.uk /Service_x72_web.pdf 200
41304
option247.uk /favicon.ico 200
41307
option247.uk /index.html 200
41901
option247.uk / 200
42237
option247.uk /css/multiColumnTemplate.css 200
42238
option247.uk /O247images/melkshamnews.png 200
42239
option247.uk /O247images/email.png 200
42240
option247.uk /O247images/facebook.png 200
42241
option247.uk /O247images/bbcwiltshire.jpeg 200
42242
option247.uk /O247images/O247sidebar.jpg 200
42243
option247.uk /O247images/1.jpg 200
42244
option247.uk /O247images/4.jpg 200
42245
option247.uk /O247images/twitter.png 200
42246
option247.uk /O247images/2.jpg 200
42247
option247.uk /O247images/woman1.jpg 200
42248
option247.uk /O247images/3.jpg 200
42249
option247.uk /O247images/man2.jpg 200
42250
option247.uk /O247images/man3.jpg 200
42251
option247.uk /O247images/woman4.jpg 200
42252
option247.uk /o247_2.jpg 200
43506
option247.uk /O247images/1.jpg 200
43513
option247.uk / 200
45035
option247.uk /Service_x72_web.pdf 200
45049
option247.uk / 200
45261
option247.uk /css/multiColumnTemplate.css 200
45262
option247.uk /O247images/O247sidebar.jpg 200
45263
option247.uk /O247images/facebook.png 200
45264
option247.uk /O247images/bbcwiltshire.jpeg 200
45265
option247.uk /O247images/email.png 200
45266
option247.uk /O247images/melkshamnews.png 200
45267
option247.uk /O247images/man2.jpg 200
45268
option247.uk /O247images/3.jpg 200
45269
option247.uk /O247images/1.jpg 200
45270
option247.uk /O247images/4.jpg 200
45271
option247.uk /O247images/woman4.jpg 200
45272
option247.uk /O247images/man3.jpg 200
45273
option247.uk /O247images/2.jpg 200
45274
option247.uk /O247images/woman1.jpg 200
45275
option247.uk /O247images/twitter.png 200
45276
option247.uk /O247images/melkshamnews.png 200
45574
option247.uk /Service_x72_web.pdf 200
49969
162 matches
49999
WomanWithCat:4c grahamellis$

Learn about this subject

This module and example are covered on the following public courses:
* Learning to program in Ruby
* Ruby Programming
Also available on on site courses for larger groups

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