SHA256.hexdigest が IO オブジェクトを受け付けるようにしたらどうでしょう。
hxdgst = File.open(filename){|io| Digest::SHA256.hexdigest(io) }
と書けます。これなら StringIO や open-uri とも親和性が高い気がします。新しいメソッドを覚える必要がない。長いけど。
いやでも、Article 5 の本文によると、
Article 5
Criminalization of participation in an organized criminal group
1. Each State Party shall adopt such legislative and other measures as may be necessary to establish as criminal offences, when committed intentionally:
(a) Either or both of the following as criminal offences distinct from those involving the attempt or completion of the criminal activity:
(i) Agreeing with one or more other persons to commit a serious crime for a purpose relating directly or indirectly to the obtaining of a financial or other material benefit and, where required by domestic law, involving an act ndertaken by one of the participants in furtherance of the agreement or involving an organized criminal group;
(ii) Conduct by a person who, with knowledge of either the aim and general criminal activity of an organized criminal group or its intention to commit the crimes in question, takes an active part in:
a. Criminal activities of the organized criminal group;
b. Other activities of the organized criminal group in the knowledge that his or her participation will contribute to the achievement of the above-described criminal aim;
(b) Organizing, directing, aiding, abetting, facilitating or counselling the commission of serious crime involving an organized criminal group.
なんで、締約国は (a)(i) (共謀罪) と (b) あるいは (a)(ii) と (b) のどちらかの組合せを選んで犯罪としないといけない。Article 5 の解説を読むと
49. The approaches countries have adopted so far vary depending on historical, political and legal backgrounds. Broadly speaking, the criminalization of participation in organized criminal groups has been achieved in two different ways. Common law countries have used the offence of conspiracy, while civil law jurisdictions have used offences that proscribe an involvement in criminal organizations. Other countries combine such approaches. The Convention does not deal with prohibition of membership in specific organizations.
51. The Convention aims at meeting the need for a global response and at ensuring the effective criminalization of acts of participation in criminalgroups. Article 5 of the Convention recognizes the two main approaches to such criminalization that are cited above as equivalent. The two alternative options of article 5, paragraph 1 (a) (i) and paragraph 1 (a) (ii) were thus created to reflect the fact that some countries have conspiracy laws, while others have criminal association (association de malfaiteurs) laws. The options allow for effective action against organized criminal groups, without requiring the introduction of either notion―conspiracy or criminal association―in States that do not have the relevant legal concept. Article 5 also covers persons who assist and facilitate serious offences committed by an organized criminal group in other ways.
(a)(i) と (a)(ii) のふたつの選択肢(the options)があるのは、共謀罪は主にコモンロー体系で採用されていて、参加罪は大陸法体系で採用されているんで、どっちの法体系に属しているかで選べるように、(a)(i) と (a)(ii) を用意しました、と書いてある。だから、『「共謀罪」か「犯罪の結社」（参加罪）の概念の「両方とも」を導入する必要はないけれど、どちらか一方は導入しなければならない、という政府・与党の主張』は正しいと思う。
ただ、(a)(ii)は〈犯罪の結社への参加〉ではなくて、実際の犯罪行為への参加 (a)(ii) a. か、あるいは犯罪行為を支援する行為への参加 (a)(ii) b. のどちらかということになっている。んで、『The Convention does not deal with prohibition of membership in specific organizations.』だそうで、(a)(ii) というかこの条約は『特定の組織への参加の禁止を取り扱っていない』んだそうな。
だから、「共謀罪」を選ばない場合は、「organized criminal group」という概念は作らないといけなといけない。けど、〈犯罪結社への参加〉を罪にする必要はなくて、犯罪の実行行為(とその幇助)への参加を罪とすればいい。で、これは、従来の日本の刑法で十分対応可能なような気がする。大陸法の日本がなぜ共謀罪を採用するのかが良く分からない。
というようなことが議論されているのだろう。
http://www.unodc.org/pdf/crime/legislative_guides/02%20Legislative%20guide_TOC%20Convention.pdf#page=20
議論されていた。
http://www.shugiin.go.jp/itdb_kaigiroku.nsf/html/kaigiroku/000216420060517008.htm
